Note: This script was written using versions 3.4.0 and 1.1.447 of R and RStudio, respectively.

Project Components

The study described in this document is part of a project looking at the effects of mindfulness on graduate/professional students. In addition to this script, the following project components are publicly available:

Abstract

This study investigated the effects of a mindfulness meditation intervention on the psychological well-being of a group of graduate/professional students. Two hundred twenty-three participants were randomly assigned to either an experimental group (n = 112) or a delayed-start control group (n = 111). All participants completed a series of self-report measures designed to assess perceived well-being and affect (T1). Following the completion of these measures, the experimental group participated in a 4-week mindfulness program. At the end of this program, all participants completed the self-report measures for a second time (T2). The control group then participated in the same 4-week mindfulness program and, at the end of this program, all participants completed the self-report measures for a third and final time (T3). The completion of the mindfulness program was associated with decreases in stress, negative affect, and depression, as well as increases in resilience, non-reactivity, acting with awareness, describing, and non-judging. Based on moderation analyses, most improvements seem to have been unrelated to the amount of program engagement and length of previous meditation experience. It is, however, important to note that sample sizes in both groups were relatively small due to participant drop-out throughout the study. Consequently, though the significant findings and general trends within the data are promising, these results should be interpreted with caution and future work should consider ways in which drop-out can be minimized or mitigated.

Introduction

This document outlines the analyses from the Mindful Grad Study. Research protocol and planned analyses for this study were registered by Minda and Nielsen and can be viewed here. The purpose of this study was to investigate whether a 4-week mindfulness intervention would improve the well-being of a group of graduate/professional students.

Participants were randomly assigned to one of two conditions: an experimental condition (n = 112) or a delayed-start control condition (n = 111). At the beginning of the study (i.e. T1), all participants were asked to complete a series of self-report measures:

Responses were also collected on the Multidimensional Emotional Intelligence Assessment - Workplace (MEIA-W; a measure of emotional intelligence). Predictions regarding this measure were not made, however, and this data will not be analysed as part of the study.

After completing the above measures, participants in the experimental condition completed a 30-day mindfulness program. After the experimental group had completed the program (i.e. T2), all participants completed the above self-report measures for a second time. Following the T2 testing period, participants in the control condition completed the 30-day mindfulness program. Once the control group had completed the program (i.e. T3), all participants completed the self-report measures for a third time.

If the intervention was effective in improving well-being, analyses should reveal an interaction between time and condition such that, from T1 to T2, participants in the experimental condition experienced an increase in scores on the BRS, the positive affect subscale of the PANAS, and all subscales of the FFMQ, as well as a decrease in scores on the PSS, the negative affect subscale of the PANAS, and all subscales of the DASS. Between these two testing periods, participants in the control condition should show no change in scores on any of the measures considered; instead, participants in the control condition should demonstrate the predicted changes during T2 and T3.

1. Changes Across All Three Time Points

Our first set of analyses will look at the effect of time and condition on self-report scores across all three time points. For these analyses, we will focus exclusively on participants who provided responses to all three surveys and who actively participated in the meditation program.

Demographic Information

Table 1. Frequency-based demographic information for participants who completed all three surveys.
Control (n) Experimental (n)
Total
17 18
Gender
Male 3 4
Female 14 14
Status
Full Time 16 16
Part Time 1 2
Program
Master’s 13 14
Doctoral 3 4
Professional Degree 1 0
Meditation Experience
Yes 10 11
No 7 7
Yoga Experience
Yes 8 10
No 9 8
Tai Chi Experience
No 17 18
Continued Practice
Yes NA 11
No NA 7
Table 2. Demographic information for participants who completed all three surveys.
Condition n M SD SE CI
Meditation During the Program (Min/Week)
Control 17 52.5000 45.0791 10.9333 23.1775
Experimental 18 46.8833 32.5657 7.6758 16.1946
Meditation After the Program (Min/Week)
Control 0 NaN NA NA NA
Experimental 11 56.0909 93.9207 28.3181 63.0968

Reliabilities

Table 3. Standardized Cronbach alpha values across all three time points.
Control Condition
Experimental Condition
Conditions Combined
Measure T1 T2 T3 Overall T1 T2 T3 Overall T1 T2 T3 Overall
Perceived Stress Scale
0.87 0.87 0.80 0.86 0.81 0.84 0.89 0.87 0.84 0.89 0.86 0.88
Positive and Negative Affect Schedule
Positive Affect 0.90 0.94 0.86 0.91 0.86 0.89 0.92 0.89 0.88 0.92 0.88 0.90
Negative Affect 0.77 0.89 0.81 0.85 0.79 0.82 0.68 0.81 0.78 0.90 0.77 0.84
Brief Resilience Scale
0.92 0.93 0.88 0.91 0.92 0.91 0.91 0.92 0.92 0.92 0.90 0.91
Five Facet Mindfulness Questionnaire
Non-Reactivity 0.64 0.84 0.67 0.75 0.88 0.90 0.72 0.88 0.78 0.88 0.72 0.83
Observing 0.80 0.88 0.90 0.87 0.73 0.82 0.83 0.79 0.76 0.88 0.88 0.84
Awareness 0.91 0.92 0.82 0.90 0.86 0.80 0.84 0.86 0.90 0.89 0.83 0.88
Describing 0.87 0.89 0.93 0.89 0.86 0.89 0.85 0.87 0.86 0.89 0.89 0.88
Non-Judging 0.78 0.84 0.84 0.83 0.83 0.86 0.91 0.88 0.83 0.85 0.87 0.85
Depression, Anxiety, and Stress Scale
Depression 0.89 0.90 0.84 0.88 0.93 0.91 0.92 0.93 0.90 0.91 0.87 0.90
Anxiety 0.83 0.88 0.87 0.86 0.71 0.71 0.65 0.71 0.78 0.84 0.83 0.82
Stress 0.77 0.83 0.66 0.79 0.85 0.77 0.62 0.82 0.82 0.83 0.66 0.81

Perceived Stress Scale

Note: Figures in this document depict score distributions that are estimated based on the means and variances of scores that we measured in our sample. For all figures, time of testing (i.e. T1, T2, and/or T3) is displayed on the horizontal axis, scale scores are displayed on the vertical axis, and dots and whiskers represent the sample means and standard deviations, respectively. The control group is depicted in green and the experimental group is depicted in yellow.

For participants in the experimental condition, both T2 (MT2 = 35.56, SDT2 = 5.75) and T3 (MT3 = 34.78, SDT3 = 6.66) scores on the PSS were found to be significantly lower than T1 scores (MT1 = 42.28, SDT1 = 6.12; p = 0.01 and p = 0.002, respectively). A significant score difference was not observed between T2 and T3 (p = 0.92).

For participants in the control condition, an effect of time was not observed.

Positive and Negative Affect Schedule

Positive Affect

Scores on this measure were not found to be affected by time or condition.

Negative Affect

For participants in the experimental condition, both T2 (MT2 = 20, SDT2 = 4.78) and T3 (MT3 = 20, SDT3 = 4.46) scores on the PANAS-Negative were found to be significantly lower than T1 scores (MT1 = 25.28, SDT1 = 6.23; p = 0.01 and p = 0.01, respectively). A significant score difference was not observed between T2 and T3 (p = 1).

For participants in the control condition, an effect of time was not observed.

Brief Resilience Scale

Scores on this measure were not found to be affected by time or condition.

Five Facet Mindfulness Questionnaire

Non-Reactivity

For participants in the experimental condition, T3 (MT3 = 16.28, SDT3 = 2.47) scores on the FFMQ-24-Non-Reactivity were found to be significantly higher than T1 scores (MT1 = 12.33, SDT1 = 3.79; p = 0.01). A significant score difference was not observed between T1 and T2 (MT2 = 14.83, SDT2 = 4.36; p = 0.11) or T2 and T3 (p = 0.46).

For participants in the control condition, an effect of time was not observed.

Observing

Scores on this measure were not found to be affected by time or condition.

Acting with Awareness

For participants in the experimental condition, both T2 (MT2 = 16.28, SDT2 = 2.99) and T3 (MT3 = 16.78, SDT3 = 3) scores on the FFMQ-24-Awareness were found to be significantly higher than T1 scores (MT1 = 13.33, SDT1 = 3.12; p = 0.01 and p = 0.004, respectively). A significant score difference was not observed between T2 and T3 (p = 0.87).

For participants in the control condition, an effect of time was not observed.

Describing

Scores on this measure were not found to be affected by time or condition.

Non-Judging

For participants in the experimental condition, T3 (MT3 = 16.33, SDT3 = 4.3) scores on the FFMQ-24-Non-Judging were found to be significantly higher than T1 scores (MT1 = 12.28, SDT1 = 4.06; p = 0.01). A significant score difference was not observed between T1 and T2 (MT2 = 15.22, SDT2 = 3.9) or T2 and T3 (p = 0.09 and p = 0.7, respectively).

For participants in the control condition, an effect of time was not observed.

Depression, Anxiety, and Stress Scale

Depression

When averaged across both groups, T3 (MT3 = 6.23, SDT3 = 5.88) scores on the DASS-Depression were found to be significantly lower than T1 scores (MT1 = 10.06, SDT1 = 9.22; p = 0.02). A significant score difference was not observed between T1 and T2 (MT2 = 8, SDT2 = 8.01) or T2 and T3 (p = 0.05 and p = 0.13, respectively).

An effect of condition was not observed.

Anxiety

Scores on this measure were not found to be affected by time or condition.

Stress

For participants in the experimental condition, T3 scores (MT3 = 10.89, SDT3 = 4.66) on the DASS-21-Stress were found to be significantly lower than T1 scores (MT1 = 17.11, SDT1 = 9.39; p = 0.03). A significant score difference was not observed between T1 and T2 (MT2 = 11.67, SDT2 = 6.9) or T2 and T3 (p = 0.07 and p = 0.94, respectively).

For participants in the control condition, an effect of time was not observed.

Summary of Results

The following results were found to be statistically significant:

  • Perceived Stress Scale

    • a decrease in perceived stress from T1 to both T2 and T3 for participants in the experimental condition (p = 0.01 and p = 0.002, respectively)

  • Positive and Negative Affect Schedule

    • a reduction in negative affect from T1 to both T2 and T3 for participants in the experimental condition (p = 0.01 and p = 0.01, respectively)

  • Five Facet Mindfulness Questionnaire

    • an increase in non-reactivity from T1 to T3 for participants in the experimental condition (p = 0.01)

    • an increase in acting with awareness from T1 to both T2 and T3 for participants in the experimental condition (p = 0.01 and p = 0.004, respectively)

    • an increase in non-judging from T1 to T3 (p = 0.01)

  • Depression, Anxiety, and Stress Scale

    • a reduction in depression from T1 to T3 (p = 0.02)

    • a reduction in stress from T1 to T3 for participants in the experimental condition (p = 0.03)

Conclusion

Initial analyses revealed changes in many of the variables considered. Although these changes were all found to occur in the predicted direction (e.g. a decrease in things like stress and depression and an increase in mindful cognition), they seem to have occurred either only for the experimental condition or over time regardless of condition. If the meditation program was, in fact, responsible for the observed changes, it is unclear why no changes were found to occur in the control condition. One possibility is that the effects (or lack thereof) were influenced or obscured by small sample sizes (nControl = 17 and nExperimental = 18). We will assess this possibility through a series of exploratory follow-up analyses looking at the effects of time and condition on self-report scores across T1 and T2 and the effects of time on control scores across T2 and T3. Between T1 and T2, participants in the experimental condition completed the meditation program while participants in the control condition did nothing. Between T2 and T3, participants in the control condition completed the meditation program. The rate of participant drop-out between these individual time points was smaller than across T1 and T3. Consequently, additional analyses with larger samples may help to clarify which effects can be attributed to the meditation program.

2. Changes Across the First Two Time Points

Our second set of analyses will look at the effect of time and condition on self-report scores across the first two time points (i.e. T1 and T2). For these analyses, we will focus on participants who provided responses to the first two surveys and, for the experimental group, those who actively participated in the meditation program.

Demographic Information

Table 4. Frequency-based demographic information for participants who completed the first two surveys.
Control (n) Experimental (n)
Total
48 33
Gender
Male 12 5
Female 36 28
Status
Full Time 47 29
Part Time 1 3
Other 0 1
Program
Master’s 25 20
Doctoral 19 11
Professional Degree 4 1
Graduate Diploma 0 1
Meditation Experience
Yes 27 18
No 21 15
Yoga Experience
Yes 21 16
No 27 17
Tai Chi Experience
No 48 33
Table 5. Mins/Week Spent Meditating for participants who completed the first two surveys.
Condition n M SD SE CI
Control 48 NA NA NA NA
Experimental 33 49.7015 42.0667 7.3229 14.9162

Reliabilities

Table 6. Standardized Cronbach alpha values across the first two time points.
Control Condition
Experimental Condition
Conditions Combined
Measure T1 T2 Overall T1 T2 Overall T1 T2 Overall
Perceived Stress Scale
0.85 0.86 0.85 0.85 0.83 0.85 0.85 0.87 0.86
Positive and Negative Affect Schedule
Positive Affect 0.90 0.91 0.91 0.88 0.91 0.90 0.89 0.91 0.90
Negative Affect 0.83 0.89 0.86 0.82 0.77 0.83 0.82 0.88 0.85
Brief Resilience Scale
0.89 0.91 0.89 0.92 0.89 0.90 0.90 0.90 0.90
Five Facet Mindfulness Questionnaire
Non-Reactivity 0.77 0.83 0.80 0.86 0.85 0.86 0.81 0.84 0.83
Observing 0.77 0.91 0.85 0.64 0.84 0.75 0.74 0.90 0.83
Awareness 0.90 0.89 0.89 0.89 0.80 0.87 0.90 0.87 0.88
Describing 0.87 0.89 0.88 0.87 0.87 0.87 0.87 0.88 0.87
Non-Judging 0.80 0.84 0.82 0.86 0.89 0.88 0.83 0.86 0.84
Depression, Anxiety, and Stress Scale
Depression 0.86 0.86 0.86 0.89 0.90 0.90 0.87 0.88 0.87
Anxiety 0.81 0.82 0.82 0.71 0.74 0.73 0.78 0.80 0.79
Stress 0.71 0.84 0.79 0.81 0.78 0.81 0.76 0.83 0.80

Perceived Stress Scale

For those in the experimental condition, T2 scores (MT2 = 35.97, SDT2 = 5.64) on the PSS were found to be significantly lower than T1 scores (MT1 = 40.94, SDT1 = 6.72); t (32) = 5, p < .001, d = 0.87.

For participants in the control condition, an effect of time was not observed.

Positive and Negative Affect Schedule

Positive Affect

Scores on this measure were not found to be affected by time or condition.

Negative Affect

For those in the experimental condition, T2 scores (MT2 = 19.73, SDT2 = 4.29) on the PANAS-Negative were found to be significantly lower than T1 scores (MT1 = 24.52, SDT1 = 6.61); t (32) = 4.18, p < .001, d = 0.73.

For participants in the control condition, an effect of time was not observed.

Brief Resilience Scale

For those in the experimental condition, T2 scores (MT2 = 3.46, SDT2 = 0.72) on the BRS were found to be significantly higher than T1 scores (MT1 = 3.21, SDT1 = 0.84); t (32) = -2.55, p = 0.03, d = -0.44.

For those in the control condition, an effect of time was not observed.

Five Facet Mindfulness Questionnaire

Non-Reactivity

For those in the experimental condition, T2 scores (MT2 = 15.18, SDT2 = 3.54) on the FFMQ-Non-Reactivity were found to be significantly higher than T1 scores (MT1 = 12.33, SDT1 = 3.45); t (32) = -4.76, p < .001, d = -0.83.

For those in the control condition, an effect of time was not observed.

Observing

Participants in the experimental condition (ME = 14.52, SDE = 2.87) scored significantly higher on the FFMQ-Observing than participants in the control condition (MC = 12.66, SDC = 3.79); F (1, 79) = 7.28, p = 0.01, \(\eta^2_{G}\) = 0.08.

An effect of time was not observed.

Acting with Awareness

For those in the experimental condition, T2 scores (MT2 = 16.24, SDT2 = 3.02) on the FFMQ-Awareness were found to be significantly higher than T1 scores (MT1 = 14.42, SDT1 = 3.66); t (32) = -2.8, p = 0.02, d = -0.49.

For those in the control condition, an effect of time was not observed.

Describing

When averaged across both groups, T2 scores (MT2 = 16.8, SDT2 = 4.01) on the FFMQ-Describing were found to be significantly higher than T1 scores (MT1 = 16.11, SDT1 = 4.18); F (1, 79) = 4.67, p = 0.03, \(\eta^2_{G}\) = 0.01.

An effect of condition was not observed.

Non-Judging

For those in the experimental condition, T2 scores (MT2 = 16.18, SDT2 = 3.96) on the FFMQ-Non-Judging were found to be significantly higher than T1 scores (MT1 = 13.24, SDT1 = 4.25); t (32) = -6.07, p < .001, d = -1.06.

For those in the control condition, an effect of time was not observed.

Depression, Anxiety, and Stress Scale

Depression

For those in the experimental condition, T2 scores (MT2 = 6.61, SDT2 = 6.9) on the DASS-Depression were found to be significantly lower than T1 scores (MT1 = 10.42, SDT1 = 8.71); Z = 3.12, p = 0.003, r = 0.54.

For those in the control condition, an effect of time was not observed.

Anxiety

Scores on this measure were not found to be affected by time or condition.

Stress

For those in the experimental condition, T2 scores (MT2 = 11.27, SDT2 = 6.72) on the DASS-Stress were found to be significantly lower than T1 scores (MT1 = 15.64, SDT1 = 8.15); Z = 3.02, p = 0.004, r = 0.53.

For those in the control condition, an effect of time was not observed.

Summary of Results

The following results were found to be statistically significant:

  • Perceived Stress Scale

    • a decrease in perceived stress from T1 to T2 for participants in the experimental condition (p < .001)

  • Positive and Negative Affect Schedule

    • a reduction in negative affect from T1 to T2 for participants in the experimental condition (p < .001)

  • Brief Resilience Scale

    • an increase in resilience from T1 to T2 for participants in the experimental condition (p = 0.03)

  • Five Facet Mindfulness Questionnaire

    • an increase in non-reactivity from T1 to T2 for participants in the experimental condition (p < .001)

    • greater observing for participants in the experimental condition compared to participants in the control condition (p = 0.01)

    • an increase in awareness from T1 to T2 for participants in the experimental condition (p = 0.02)

    • an increase in describing from T1 to T2 (p = 0.03)

    • an increase in non-judging from T1 to T2 for participants in the experimental condition (p < .001)

  • Depression, Anxiety, and Stress Scale

    • a reduction in depression from T1 to T2 for participants in the experimental condition (p = 0.003)

    • a reduction in stress from T1 to T2 for participants in the experimental condition (p = 0.004)

Conclusion

A second set of analyses provided support for most of the hypotheses made in this study. In particular, participants in the experimental condition reported a decrease in stress (measured by both the PSS and the DASS), negative affect, and depression, as well as an increase in resilience, non-reactivity, acting with awareness, and non-judgmentalness following the completion of the mindfulness intervention. In contrast, participants in the control condition reported no change from T1 to T2 in any of the variables considered. These results, therefore, suggest that the meditation program was effective in enhancing mindful cognition (measured by the FFMQ) and improving participants’ psychological well-being. Another possibility, however, is that participants in the control condition were significantly different at T1 from those in the experimental condition. By this logic, T1 to T2 changes may not have been observed in control participants simply because they were initially low/high in things like stress/positive affect. This next set of analyses will investigate this possibility by assessing between-group differences at T1.

3. Between-Group Differences During the First Testing Period

Our third set of analyses will look at the effect of condition on T1 scores. Because we are specifically interested in testing an alternate interpretation of the results from the previous section, we will limit the present analysis to the participants included in the previous analysis (i.e. Analysis 2).

Perceived Stress Scale

A significant difference in T1 PSS scores was not observed between the control (MC = 40.52, SDC = 6.76) and experimental (ME = 40.94, SDE = 6.72) conditions; Z = -0.39, p = 0.7, r = 0.04.

Positive and Negative Affect Schedule

Positive Affect

A significant difference in T1 PANAS-Positive scores was not observed between the control (MC = 33.21, SDC = 7.52) and experimental (ME = 32.27, SDE = 6.28) conditions; t (79) = 0.59, p = 0.56, d = 0.13.

Negative Affect

A significant difference in T1 PANAS-Negative scores was not observed between the control (MC = 24.29, SDC = 7.07) and experimental (ME = 24.52, SDE = 6.61) conditions; t (79) = -0.14, p = 0.89, d = -0.03..

Brief Resilience Scale

A significant difference in T1 BRS scores was not observed between the control (MC = 3.44, SDC = 0.78) and experimental (ME = 3.21, SDE = 0.84) conditions; t (79) = 1.24, p = 0.22, d = 0.28.

Five Facet Mindfulness Questionnaire

Non-Reactivity

A significant difference in T1 FFMQ-Non-Reactivity scores was not observed between the control (MC = 13.83, SDC = 3.63) and experimental (ME = 12.33, SDE = 3.45) conditions; t (79) = 1.86, p = 0.07, d = 0.42.

Observing

A significant difference in T1 FFMQ-Observing scores was not observed between the control (MC = 12.71, SDC = 3.52) and experimental (ME = 14, SDE = 2.6) conditions; t (78.57) = -1.9, p = 0.06, d = -0.41.

Acting with Awareness

A significant difference in T1 FFMQ-Awareness scores was not observed between the control (MC = 14.94, SDC = 4.46) and experimental (ME = 14.42, SDE = 3.66) conditions; t (79) = 0.55, p = 0.59, d = 0.12.

Describing

A significant difference in T1 FFMQ-Describing scores was not observed between the control (MC = 16.23, SDC = 4.53) and experimental (ME = 15.94, SDE = 3.67) conditions; t (79) = 0.3, p = 0.76, d = 0.07.

Non-Judging

Control participants (MC = 15.54, SDC = 4.61) scored significantly higher on the FFMQ-Non-Judging at T1 than did experimental participants (ME = 13.24, SDE = 4.25); t (79) = 2.28, p = 0.03, d = 0.51. In fact, control participants’ T1 scores were found to be similar to experimental participants’ T2 scores; t (79) = -0.65, p = 0.52, d = -0.15.

Depression, Anxiety, and Stress Scale

Depression

A significant difference in T1 DASS-Depression scores was not observed between the control (MC = 9.42, SDC = 7.73) and experimental (ME = 10.42, SDE = 8.71) conditions; Z = -0.48, p = 0.64, r = 0.05.

Anxiety

A significant difference in T1 DASS-Anxiety scores was not observed between the control (MC = 7.96, SDC = 7.36) and experimental (ME = 7.64, SDE = 5.8) conditions; Z = -0.31, p = 0.76, r = 0.03.

Stress

A significant difference in T1 DASS-Stress scores was not observed between the control (MC = 13.75, SDC = 6.76) and experimental (ME = 15.64, SDE = 8.15) conditions; Z = -1.11, p = 0.27, r = 0.12.

Summary of Results

The following results were found to be statistically significant:

  • Five Facet Mindfulness Questionnaire

    • control participants displayed a greater degree of non-judging at T1 than did experimental participants (p = 0.03) and, in fact, displayed levels at T1 that were similar to the levels displayed by the experimental group at T2 (p = 0.52)

Conclusion

This third set of analyses revealed that control participants displayed a level of non-judging at T1 that was greater than the level displayed at T1 by those in the experimental condition; in fact, T1 control scores on the FFMQ-Non-Judging were similar to T2 experimental scores on this measure. This suggests that, for some reason, participants in the experimental condition began the study with a lower level of non-judging than those in the control condition. Following the intervention, experimental participants’ level of non-judging increased to that of the control condition. We cannot, however, state with certainty that this increase in non-judging was due solely to the mindfulness intervention because:

  1. there may be some innate between-group difference that both effects trait non-judging and moderates how effective the program is in altering this characteristic at a state level, and/or

  2. the observed T1-T2 change in experimental group non-judging may have been caused by the passage of time, the effects of which were not found to be significant for those in the control condition simply because the control group began the study with a higher degree of non-judging.

With respect to the FFMQ-Non-Judging, therefore, it is unclear if the effects observed in the previous set of analyses are attributable to the mindfulness intervention, the passage of time, or some other unknown factor.

With the exception of the FFMQ-Non-Judging though, participants in both groups scored similarly at T1 on all of the measures considered. These results, in combination with the results from the previous section, suggest that all participants began at similar levels of stress, affect, etc., and that something occurred between T1 and T2 to drive a change in these variables for participants in the experimental condition but not for those in the control condition. These results, therefore, provide additional support for the efficacy of the mindfulness intervention in improving psychological well-being.

We will now assess this conclusion further through another series of exploratory analyses looking at the effects of time on self-report scores across T2 and T3. If the mindfulness intervention is effective in altering the outcome measures considered in this study, participants in the control condition should have experienced changes between T2 and T3 (following their completion of the mindfulness intervention) that were similar to those observed between T1 and T2 for those in the experimental condition. Note, however, that there is a major caveat to this next analysis, namely that there is no control group with which the control group may be adequately compared to. Although we have T2-T3 data for participants in the experimental condition, experimental participants may have continued to practice the meditations from the mindfulness intervention throughout this period of time and/or their T3 responses may have been influenced by long-term carry-over effects of the program. Consequently, the experimental condition will be excluded from the next set of analyses but any results obtained should be interpreted with caution.

4. Control Changes Across the Last Two Time Points

Our fourth set of analyses will look at the effect of time on control participant self-report scores across the last two time points (i.e. T2 and T3). For these analyses, we will focus on control participants who provided responses to the last two surveys and who actively participated in the meditation program.

Demographic Information

Table 7. Frequency-based demographic information for control participants who completed the last two surveys.
Gender
Male 3
Female 15
Status
Full Time 17
Part Time 1
Program
Master’s 14
Doctoral 3
Professional Degree 1
Meditation Experience
Yes 11
No 7
Yoga Experience
Yes 9
No 9
Tai Chi Experience
No 18
Table 8. Mins/Week Spent Meditating for control participants who completed the last two surveys.
n M SD SE CI
18 52.3611 43.7371 10.3089 21.75

Reliabilities

Table 9. Standardized Cronbach alpha values across the last two time points in Study 2.
Measure T2 T3 Overall
Perceived Stress Scale
0.86 0.79 0.85
Positive and Negative Affect Schedule
Positive Affect 0.94 0.88 0.92
Negative Affect 0.89 0.80 0.87
Brief Resilience Scale
0.93 0.88 0.91
Five Facet Mindfulness Questionnaire
Non-Reactivity 0.84 0.66 0.79
Observing 0.87 0.90 0.89
Awareness 0.91 0.81 0.88
Describing 0.88 0.93 0.91
Non-Judging 0.83 0.84 0.85
Depression, Anxiety, and Stress Scale
Depression 0.90 0.83 0.87
Anxiety 0.88 0.86 0.87
Stress 0.82 0.66 0.78

Perceived Stress Scale

For those in the control condition, T3 scores (MT3 = 38.39, SDT3 = 6.53) on the PSS were found to be significantly lower than T2 scores (MT2 = 43.39, SDT2 = 7.91); t (17) = 4.48, p < .001, d = 1.05.

Positive and Negative Affect Schedule

Positive Affect

For those in the control condition, an effect of time was not observed.

Negative Affect

For those in the control condition, T3 scores (MT3 = 21.56, SDT3 = 5.83) on the PANAS-Negative were found to be significantly lower than T2 scores (MT2 = 26.61, SDT2 = 8.8); t (17) = 3.23, p = 0.005, d = 0.76.

Brief Resilience Scale

For those in the control condition, an effect of time was not observed.

Five Facet Mindfulness Questionnaire

Non-Reactivity

For those in the control condition, an effect of time was not observed.

Observing

For those in the control condition, an effect of time was not observed.

Acting with Awareness

For those in the control condition, an effect of time was not observed.

Describing

For those in the control condition, T3 scores (MT3 = 17.72, SDT3 = 4.3) on the FFMQ-Describing were found to be significantly higher than T2 scores (MT2 = 15.5, SDT2 = 4.37); t (17) = -3.34, p = 0.004, d = -0.79.

Non-Judging

For those in the control condition, T3 scores (MT3 = 17.06, SDT3 = 4.08) on the FFMQ-Non-Judging were found to be significantly higher than T2 scores (MT2 = 14.11, SDT2 = 4.65); t (17) = -3.02, p = 0.01, d = -0.71.

Depression, Anxiety, and Stress Scale

Depression

For those in the control condition, an effect of time was not observed.

Anxiety

For those in the control condition, an effect of time was not observed.

Stress

For those in the control condition, an effect of time was not observed.

Summary of Results

The following results were found to be statistically significant with respect to the control group:

  • Perceived Stress Scale

    • a decrease in perceived stress from T2 to T3 (p < .001)

  • Positive and Negative Affect Schedule

    • a reduction in negative affect from T2 to T3 (p = 0.02)

  • Five Facet Mindfulness Questionnaire

    • an increase in describing and non-judging from T2 to T3 (p = 0.004 and p = 0.01)

Conclusion

This fourth set of analyses provided some additional support for the conclusion that the mindfulness intervention was effective in improving participants’ well-being; all effects, whether significant or not, were found to occur in the expected direction. As previously discussed, however, the results from this set of analyses should be interpreted with caution, as the lack of a comparison group means that we cannot account for factors such as the passage of time or time of assessment. Furthermore, the size of the sample considered here is fairly small. As in the first set of analyses, a small sample size may explain why, compared to the second set of analyses, these fourth tests revealed fewer significant findings. Another possibility is that experimental participants entered the program with a different baseline on the measures considered than control participants. In other words, control participants may not have been able to change as much as experimental participants because they began the program with high levels of positive affect/resilience, etc. and low levels of stress/depression, etc. In our next set of analyses, we will assess this possibility by conducting a comparison between T1-Experimental scores and T2-Control scores.

5. Experimental and Control Baseline Comparisons

Our fifth set of analyses will look at potential baseline differences between the two conditions (i.e. differences between T1-Experimental and T2-Control scores). For these analyses, we will focus on participants who actively participated in the mindfulness program and, for experimental/control participants, those who provided responses to the first two/last two surveys (i.e. the experimental participants from Analysis 2 and the control participants from Analysis 4).

Perceived Stress Scale

A significant difference in PSS baselines was not observed between the control and experimental conditions; t (49) = 1.17, p = 0.25, d = -0.33.

Positive and Negative Affect Schedule

Positive Affect

A significant difference in PANAS-Positive baselines was not observed between the control and experimental conditions; t (26.85) = 0.65, p = 0.52, d = -0.19.

Negative Affect

A significant difference in PANAS-Negative baselines was not observed between the control and experimental conditions; t (49) = 0.96, p = 0.34, d = -0.26.

Brief Resilience Scale

A significant difference in BRS baselines was not observed between the control and experimental conditions; t (49) = 0.67, p = 0.51, d = -0.19.

Five Facet Mindfulness Questionnaire

Non-Reactivity

A significant difference in FFMQ-Non-Reactivity baselines was not observed between the control and experimental conditions; t (49) = 0.58, p = 0.57, d = -0.16.

Observing

A significant difference in FFMQ-Observing baselines was not observed between the control and experimental conditions; t (25.23) = -1.72, p = 0.1, d = 0.5.

Acting with Awareness

A significant difference in FFMQ-Awareness baselines was not observed between the control and experimental conditions; t (49) = 0.68, p = 0.5, d = -0.19.

Describing

A significant difference in FFMQ-Describing baselines was not observed between the control and experimental conditions; t (49) = -0.38, p = 0.7, d = 0.11.

Non-Judging

A significant difference in FFMQ-Non-Judging baselines was not observed between the control and experimental conditions; t (49) = 0.67, p = 0.5, d = -0.19.

Depression, Anxiety, and Stress Scale

Depression

A significant difference in DASS-Depression baselines was not observed between the control and experimental conditions; Z = -0.16, p = 0.88, r = 0.02.

Anxiety

A significant difference in DASS-Anxiety baselines was not observed between the control and experimental conditions; Z = 0.21, p = 0.84, r = 0.03.

Stress

A significant difference in DASS-Stress baselines was not observed between the control and experimental conditions; t (49) = 0.88, p = 0.38, d = -0.25.

Conclusion

This set of analyses revealed that experimental and control participants began their respective programs with similar baselines on all measures considered. It is unlikely, therefore, that control participants displayed fewer changes than experimental participants simply because they began the program with different baselines on each measure.

In our next set of analyses, we will assess if any of the pre- to post-intervention changes are related to the length of previous meditation experience or the degree of intervention participation.

6. Relationship with Other Variables - All Participants

Our sixth set of analyses will assess the potential relationship between changes in the outcome scores and both level of participation and length of previous meditation experience. We will only include data from participants who actively participated in the meditation program and who completed the appropriate surveys (i.e. the experimental and control participants from the second and fourth set of analyses, respectively).

Moderation

Moderation was tested via the method described in Case 2 of Judd et al. (2001). According to this method, moderation in a within-subject design can be estimated by performing a regression analysis with score changes as the dependent variable and the suspected moderator as the independent variable. In this case, a significant independent variable coefficient indicates moderation.

Perceived Stress Scale

  1. Previous Experience

Previous experience was found to explain 0.93% of the change in PSS scores; R2 = 0.01, F(1, 45) = 0.42, p = 0.52. Length of previous experience is not a significant moderator of PSS change; \(\beta\) = -0.16, t = -0.65, p = 0.52.

  1. Program Participation

Program participation was found to explain 1.84% of the change in PSS scores; R2 = 0.02, F(1, 49) = 0.92, p = 0.34. Time spent meditating is not a significant moderator of PSS change; \(\beta\) = -0.02, t = -0.96, p = 0.34.

Positive and Negative Affect Schedule

Positive Affect

  1. Previous Experience

Previous experience was found to explain 0.66% of the change in PANAS-Positive scores; R2 = 0.01, F(1, 45) = 0.3, p = 0.59. Length of previous experience is not a significant moderator of PANAS-Positive change; \(\beta\) = 0.14, t = 0.55, p = 0.59.

  1. Program Participation

Program participation was found to explain 0.78% of the change in PANAS-Positive scores; R2 = 0.01, F(1, 49) = 0.39, p = 0.54. Time spent meditating is not a significant moderator of PANAS-Positive change; \(\beta\) = 0.01, t = 0.62, p = 0.54.

Negative Affect

  1. Previous Experience

Previous experience was found to explain 4.52% of the change in PANAS-Negative scores; R2 = 0.05, F(1, 45) = 2.13, p = 0.15. Length of previous experience is not a significant moderator of PANAS-Negative change; \(\beta\) = 0.45, t = 1.46, p = 0.15.

  1. Program Participation

Program participation was found to explain 1.25% of the change in PANAS-Negative scores; R2 = 0.01, F(1, 49) = 0.62, p = 0.43. Time spent meditating is not a significant moderator of PANAS-Negative change; \(\beta\) = -0.02, t = -0.79, p = 0.43.

Brief Resilience Scale

  1. Previous Experience

Previous experience was found to explain 0.17% of the change in BRS scores; R2 = 0, F(1, 45) = 0.07, p = 0.79. Length of previous experience is not a significant moderator of BRS change; \(\beta\) = -0.01, t = -0.27, p = 0.79.

  1. Program Participation

Program participation was found to explain 3.04% of the change in BRS scores; R2 = 0.03, F(1, 49) = 1.53, p = 0.22. Time spent meditating is not a significant moderator of BRS change; \(\beta\) = 0, t = -1.24, p = 0.22.

Five Facet Mindfulness Questionnaire

Non-Reactivity

  1. Previous Experience

Previous experience was found to explain 2.88% of the change in FFMQ-Non-Reactivity scores; R2 = 0.03, F(1, 45) = 1.33, p = 0.25. Length of previous experience is not a significant moderator of FFMQ-Non-Reactivity change; \(\beta\) = -0.19, t = -1.15, p = 0.25.

  1. Program Participation

Program participation was found to explain 0.6% of the change in FFMQ-Non-Reactivity scores; R2 = 0.01, F(1, 49) = 0.3, p = 0.59. Time spent meditating is not a significant moderator of FFMQ-Non-Reactivity change; \(\beta\) = 0.01, t = 0.55, p = 0.59.

Observing

  1. Previous Experience

Previous experience was found to explain 3.25% of the change in FFMQ-Observing scores; R2 = 0.03, F(1, 45) = 1.51, p = 0.22. Length of previous experience is not a significant moderator of FFMQ-Observing change; \(\beta\) = -0.14, t = -1.23, p = 0.23.

  1. Program Participation

Program participation was found to explain 12.03% of the change in FFMQ-Observing scores; R2 = 0.12, F(1, 49) = 6.7, p = 0.01. Time spent meditating is a significant moderator of FFMQ-Observing change, meaning that participants who meditated more demonstrated more positive change over time; \(\beta\) = 0.02, t = 2.59, p = 0.01. This relationship is plotted below.

Acting with Awareness

  1. Previous Experience

Previous experience was found to explain 2.72% of the change in FFMQ-Awareness scores; R2 = 0.03, F(1, 45) = 1.26, p = 0.27. Length of previous experience is not a significant moderator of FFMQ-Awareness change; \(\beta\) = -0.19, t = -1.12, p = 0.27.

  1. Program Participation

Program participation was found to explain 0.29% of the change in FFMQ-Awareness scores; R2 = 0, F(1, 49) = 0.14, p = 0.71. Time spent meditating is not a significant moderator of FFMQ-Awareness change; \(\beta\) = 0, t = 0.38, p = 0.71.

Describing

  1. Previous Experience

Previous experience was found to explain 0.32% of the change in FFMQ-Describing scores; R2 = 0, F(1, 45) = 0.14, p = 0.71. Length of previous experience is not a significant moderator of FFMQ-Describing change; \(\beta\) = 0.05, t = 0.38, p = 0.71.

  1. Program Participation

Program participation was found to explain 0.26% of the change in FFMQ-Describing scores; R2 = 0, F(1, 49) = 0.13, p = 0.72. Time spent meditating is not a significant moderator of FFMQ-Describing change; \(\beta\) = 0, t = -0.36, p = 0.72.

Non-Judging

  1. Previous Experience

Previous experience was found to explain 0.4% of the change in FFMQ-Non-Judging scores; R2 = 0, F(1, 45) = 0.18, p = 0.67. Length of previous experience is not a significant moderator of FFMQ-Non-Judging change; \(\beta\) = -0.07, t = -0.43, p = 0.67.

  1. Program Participation

Program participation was found to explain 0.51% of the change in FFMQ-Non-Judging scores; R2 = 0.01, F(1, 49) = 0.25, p = 0.62. Time spent meditating is not a significant moderator of FFMQ-Non-Judging change; \(\beta\) = 0.01, t = 0.5, p = 0.62.

Depression, Anxiety, and Stress Scale

Depression

  1. Previous Experience

Previous experience was found to explain 0.01% of the change in DASS-Depression scores; R2 = 0, F(1, 45) = 0.01, p = 0.94. Length of previous experience is not a significant moderator of DASS-Depression change; \(\beta\) = -0.02, t = -0.07, p = 0.94.

  1. Program Participation

Program participation was found to explain 7.45% of the change in DASS-Depression scores; R2 = 0.07, F(1, 49) = 3.94, p = 0.05. Time spent meditating is not a significant moderator of DASS-Depression change; \(\beta\) = -0.04, t = -1.99, p = 0.05.

Anxiety

  1. Previous Experience

Previous experience was found to explain 0.15% of the change in DASS-Anxiety scores; R2 = 0, F(1, 45) = 0.07, p = 0.79. Length of previous experience is not a significant moderator of DASS-Anxiety change; \(\beta\) = -0.07, t = -0.26, p = 0.79.

  1. Program Participation

Program participation was found to explain 1.7% of the change in DASS-Anxiety scores; R2 = 0.02, F(1, 49) = 0.85, p = 0.36. Time spent meditating is not a significant moderator of DASS-Anxiety change; \(\beta\) = -0.02, t = -0.92, p = 0.36.

Stress

  1. Previous Experience

Previous experience was found to explain 7.44% of the change in DASS-Stress scores; R2 = 0.07, F(1, 45) = 3.62, p = 0.06. Length of previous experience is not a significant moderator of DASS-Stress change; \(\beta\) = 0.63, t = 1.9, p = 0.06.

  1. Program Participation

Program participation was found to explain 2.41% of the change in DASS-Stress scores; R2 = 0.02, F(1, 49) = 1.21, p = 0.28. Time spent meditating is not a significant moderator of DASS-Stress change; \(\beta\) = -0.03, t = -1.1, p = 0.28.

Summary of Results

The following results were found to be statistically significant:

  • Five Facet Mindfulness Questionnaire

    • observing changes were moderated by time spent meditating (p = 0.01)

Conclusion

Moderation analyses suggest that changes in observing were moderated by program participation, such that more participation led to greater change across time. It’s important to note, however, that this relationship may have been unduly influenced by four exceptional participants who reported meditating for 100+ minutes per week. In the next set of analyses, therefore, we will repeat the previous analyses after removing outliers.

7. Relationship with Other Variables - Outliers Removed

Our seventh and final set of analyses will assess the potential relationship between changes in the outcome scores and both level of participation and length of previous meditation experience for those deemed to be non-outliers.

Outlier Identification

Before we begin, we will identify participants with extreme experience and participation values. These participants will be excluded from the analyses in this section.

  1. Previous Experience

The outlier values correspond to participants 64, 81, 85, 99, 104, 115, 13, 15, and 31, who reported 2 years of meditation experience; 77, who reported 7 years of meditation experience; and 63, who reported 20 years of meditation experience.

  1. Program Participation

The outlier values correspond to participants 96, 111, 123, and 51. These participants reported meditating for 138, 150, 195, and 210 minutes per week, respectively.

Moderation

As before, moderation was tested by performing regression analyses with score changes as the dependent variables and the suspected moderators as the independent variables.

Perceived Stress Scale

  1. Previous Experience

After removing outliers, previous experience was found to explain 0.02% of the change in PSS scores; R2 = 0, F(1, 34) = 0.01, p = 0.93. Length of previous experience, therefore, remains a non-significant moderator of PSS change; \(\beta\) = -0.35, t = -0.09, p = 0.93.

  1. Program Participation

After removing outliers, program participation was found to explain 1.23% of the change in PSS scores; R2 = 0.01, F(1, 45) = 0.56, p = 0.46. Time spent meditating, therefore, remains a non-significant moderator of PSS change; \(\beta\) = 0.03, t = 0.75, p = 0.46.

Positive and Negative Affect Schedule

Positive Affect

  1. Previous Experience

After removing outliers, previous experience was found to explain 2.46% of the change in PANAS-Positive scores; R2 = 0.02, F(1, 34) = 0.86, p = 0.36. Length of previous experience, therefore, remains a non-significant moderator of PANAS-Positive change; \(\beta\) = 3.56, t = 0.93, p = 0.36.

  1. Program Participation

After removing outliers, program participation was found to explain 5.4% of the change in PANAS-Positive scores; R2 = 0.05, F(1, 45) = 2.57, p = 0.12. Time spent meditating, therefore, remains a non-significant moderator of PANAS-Positive change; \(\beta\) = -0.06, t = -1.6, p = 0.12.

Negative Affect

  1. Previous Experience

After removing outliers, previous experience was found to explain 0.07% of the change in PANAS-Negative scores; R2 = 0, F(1, 34) = 0.02, p = 0.88. Length of previous experience, therefore, remains a non-significant moderator of PANAS-Negative change; \(\beta\) = -0.85, t = -0.15, p = 0.88.

  1. Program Participation

After removing outliers, program participation was found to explain 3.7% of the change in PANAS-Negative scores; R2 = 0.04, F(1, 45) = 1.73, p = 0.2. Time spent meditating, therefore, remains a non-significant moderator of PANAS-Negative change; \(\beta\) = 0.06, t = 1.31, p = 0.2.

Brief Resilience Scale

  1. Previous Experience

After removing outliers, previous experience was found to explain 3.68% of the change in BRS scores; R2 = 0.04, F(1, 34) = 1.3, p = 0.26. Length of previous experience, therefore, remains a non-significant moderator of BRS change; \(\beta\) = -0.48, t = -1.14, p = 0.26.

  1. Program Participation

After removing outliers, program participation was found to explain 7.7% of the change in BRS scores; R2 = 0.08, F(1, 45) = 3.76, p = 0.06. Time spent meditating, therefore, remains a non-significant moderator of BRS change; \(\beta\) = -0.01, t = -1.94, p = 0.06.

Five Facet Mindfulness Questionnaire

Non-Reactivity

  1. Previous Experience

After removing outliers, previous experience was found to explain 0% of the change in FFMQ-Non-Reactivity scores; R2 = 0, F(1, 34) = 0, p = 0.99. Length of previous experience, therefore, remains a non-significant moderator of FFMQ-Non-Reactivity change; \(\beta\) = -0.02, t = -0.01, p = 0.99.

  1. Program Participation

After removing outliers, program participation was found to explain 5.58% of the change in FFMQ-Non-Reactivity scores; R2 = 0.06, F(1, 45) = 2.66, p = 0.11. Time spent meditating, therefore, remains a non-significant moderator of FFMQ-Non-Reactivity change; \(\beta\) = -0.04, t = -1.63, p = 0.11.

Observing

  1. Previous Experience

After removing outliers, previous experience was found to explain 2.75% of the change in FFMQ-Observing scores; R2 = 0.03, F(1, 34) = 0.96, p = 0.33. Length of previous experience, therefore, remains a non-significant moderator of FFMQ-Observing change; \(\beta\) = 2.04, t = 0.98, p = 0.33.

  1. Program Participation

After removing outliers, program participation was found to explain 0.01% of the change in FFMQ-Observing scores; R2 = 0, F(1, 45) = 0, p = 0.96. Time spent meditating, therefore, is no longer a non-significant moderator of FFMQ-Observing change; \(\beta\) = 0, t = 0.05, p = 0.96. This relationship is plotted below.

Acting with Awareness

  1. Previous Experience

After removing outliers, previous experience was found to explain 0.65% of the change in FFMQ-Awareness scores; R2 = 0.01, F(1, 34) = 0.22, p = 0.64. Length of previous experience, therefore, remains a non-significant moderator of FFMQ-Awareness change; \(\beta\) = 1.43, t = 0.47, p = 0.64.

  1. Program Participation

After removing outliers, program participation was found to explain 0.64% of the change in FFMQ-Awareness scores; R2 = 0.01, F(1, 45) = 0.29, p = 0.59. Time spent meditating, therefore, remains a non-significant moderator of FFMQ-Awareness change; \(\beta\) = 0.01, t = 0.54, p = 0.59.

Describing

  1. Previous Experience

After removing outliers, previous experience was found to explain 3.83% of the change in FFMQ-Describing scores; R2 = 0.04, F(1, 34) = 1.35, p = 0.25. Length of previous experience, therefore, remains a non-significant moderator of FFMQ-Describing change; \(\beta\) = -2.85, t = -1.16, p = 0.25.

  1. Program Participation

After removing outliers, program participation was found to explain 1.03% of the change in FFMQ-Describing scores; R2 = 0.01, F(1, 45) = 0.47, p = 0.5. Time spent meditating, therefore, remains a non-significant moderator of FFMQ-Describing change; \(\beta\) = 0.01, t = 0.69, p = 0.5.

Non-Judging

  1. Previous Experience

After removing outliers, previous experience was found to explain 1.36% of the change in FFMQ-Non-Judging scores; R2 = 0.01, F(1, 34) = 0.47, p = 0.5. Length of previous experience, therefore, remains a non-significant moderator of FFMQ-Non-Judging change; \(\beta\) = -2.12, t = -0.69, p = 0.5.

  1. Program Participation

After removing outliers, program participation was found to explain 0.29% of the change in FFMQ-Non-Judging scores; R2 = 0, F(1, 45) = 0.13, p = 0.72. Time spent meditating, therefore, remains a non-significant moderator of FFMQ-Non-Judging change; \(\beta\) = 0.01, t = 0.36, p = 0.72.

Depression, Anxiety, and Stress Scale

Depression

  1. Previous Experience

After removing outliers, previous experience was found to explain 1.67% of the change in DASS-Depression scores; R2 = 0.02, F(1, 34) = 0.58, p = 0.45. Length of previous experience, therefore, remains a non-significant moderator of DASS-Depression change; \(\beta\) = -3.31, t = -0.76, p = 0.45.

  1. Program Participation

After removing outliers, program participation was found to explain 0% of the change in DASS-Depression scores; R2 = 0, F(1, 45) = 0, p = 0.97. Time spent meditating, therefore, remains a non-significant moderator of DASS-Depression change; \(\beta\) = 0, t = 0.04, p = 0.97.

Anxiety

  1. Previous Experience

After removing outliers, previous experience was found to explain 0.31% of the change in DASS-Anxiety scores; R2 = 0, F(1, 34) = 0.1, p = 0.75. Length of previous experience, therefore, remains a non-significant moderator of DASS-Anxiety change; \(\beta\) = -1.53, t = -0.32, p = 0.75.

  1. Program Participation

After removing outliers, program participation was found to explain 10.58% of the change in DASS-Anxiety scores; R2 = 0.11, F(1, 45) = 5.32, p = 0.03. Time spent meditating, therefore, was found to be a significant moderator of DASS-Anxiety change, meaning that participants who meditated more demonstrated more negative change over time; \(\beta\) = -0.09, t = -2.31, p = 0.03. This relationship is plotted below.

For comparison’s-sake, this relationship with all participants included is plotted below.

Stress

  1. Previous Experience

After removing outliers, previous experience was found to explain 1.98% of the change in DASS-Stress scores; R2 = 0.02, F(1, 34) = 0.69, p = 0.41. Length of previous experience, therefore, remains a non-significant moderator of DASS-Stress change; \(\beta\) = 5.07, t = 0.83, p = 0.41.

  1. Program Participation

After removing outliers, program participation was found to explain 0.35% of the change in DASS-Stress scores; R2 = 0, F(1, 45) = 0.16, p = 0.69. Time spent meditating, therefore, remains a non-significant moderator of DASS-Stress change; \(\beta\) = -0.02, t = -0.4, p = 0.69.

Summary of Results

The following results were found to be statistically significant:

  • Depression, Anxiety, and Stress Scale

    • anxiety changes were moderated by time spent meditating (p = 0.36)

Conclusion

Moderation analyses initially suggested that length of previous meditation experience was a significant moderator of change in observation. The removal of outliers, however, rendered this finding non-significant, though time spent meditating was found to be a significant moderator of the prevalence of symptoms associated with anxiety. High levels of participation, therefore, may be necessary to produce changes in observing but may simultaneously temper changes in anxiety. Ultimately though, changes in most variables considered seem to be unrelated to previous experience and degree of participation.

Overall Conclusions

For experimental participants, the completion of the mindfulness intervention was associated with a decrease in stress, negative affect, and depression, as well as an increase in resilience, non-reactivity, acting with awareness, and non-judging; additionally, control participants experienced a decrease in stress, negative affect and an increase in describing and non-judging following the program. Based on moderation analyses, most improvements seem to have been unrelated to the amount of program engagement and length of previous meditation experience. It is, however, important to note that sample sizes in both groups were relatively small due to participant drop-out throughout the study. Consequently, though the significant findings and general trends within the data are promising, these results should be interpreted with caution and future work should consider ways in which drop-out can be minimized or mitigated.