Aumer’s Mixed Model Data

author: Michael A. Erickson date: 28 August 2014 autosize: true

Introduction

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Read in the Data

Katherine wrote:

The DVs are positive, negative and success (ignore positive2)

The subject level variable should be “shirt color” The group level variable should be “group” or “manipulation”

I am having a hard time getting SPSS to find a solution and give me parameter estimates I feel confident about.

Any help would be appreciated.

## read.spss() is from the foreign library -- note the errors
## rto.raw  <- read.spss("../TRAUMA_FEB_25_2014_final merge_Edman_WATSON.sav", to.data.frame=TRUE, use.value.labels=TRUE)
## rm(rto.raw)

## spss.system.file() is from the memisc library
stu.dat <- spss.system.file('student data2.sav')
stu.dat.ds  <- as.data.set(stu.dat)
stu.dat.df  <- as.data.frame(stu.dat.ds)
## description(rto.ds)   # does not work with knitr because of unicode values

These are the data Aumer said to consider —

sort(names(stu.dat.df))
##   [1] "AGE"          "Alike_bi"     "Alike_blue"   "Alike_red"    "art"         
##   [6] "art1"         "art2"         "BI_ALIT"      "BI_ALOT"      "Bi_Att"      
##  [11] "Bi_fri"       "Bi_Good"      "Bi_Hard"      "Bi_help"      "Bi_Nice"     
##  [16] "BI_NON"       "Bi_Smart"     "Bias_Hap"     "BILIKE"       "BiPositive"  
##  [21] "BLUE_ALI"     "BLUE_ALO"     "Blue_att"     "Blue_fri"     "Blue_Good"   
##  [26] "Blue_hard"    "Blue_help"    "Blue_Nice"    "BLUE_NON"     "Blue_smart"  
##  [31] "BluePositive" "Cat"          "Change"       "CHOICE"       "CONF1"       
##  [36] "CONF10"       "CONF11"       "CONF12"       "CONF13"       "CONF2"       
##  [41] "CONF3"        "CONF4"        "CONF5"        "CONF6"        "CONF7"       
##  [46] "CONF8"        "CONF9"        "Conformity"   "Consent"      "Copy_manip"  
##  [51] "copy_scolor"  "Copy_SE1"     "Copy_SE2"     "copy_team"    "f_name7"     
##  [56] "filter_."     "Group"        "Heuristic"    "Homework"     "Homework1"   
##  [61] "KEEP_CH"      "L_name7"      "LAST_6"       "LastName"     "LastName_3"  
##  [66] "LastName_4"   "LastName_5"   "LastName2"    "math"         "math1"       
##  [71] "math2"        "memory"       "memory1"      "memory2"      "N"           
##  [76] "N_bi"         "N_blue"       "N_president"  "N_Red"        "Name"        
##  [81] "Name_3"       "Name_4"       "Name_5"       "NAME_6"       "Name2"       
##  [86] "Negative"     "New_kid"      "pattern"      "pattern1"     "pattern2"    
##  [91] "Peers_1"      "Peers_2"      "Peers_3"      "Positive"     "positive2"   
##  [96] "President"    "RED_ALIT"     "RED_ALOT"     "Red_Att"      "Red_fri"     
## [101] "Red_Good"     "Red_hard"     "Red_help"     "Red_Nice"     "RED_NON"     
## [106] "Red_Smart"    "RedPositive"  "rotation"     "rotation1"    "rotation2"   
## [111] "SE_1"         "SE_2"         "SE_CHA2"      "SE_Change"    "SE1_1"       
## [116] "SE1_10"       "SE1_11"       "SE1_12"       "SE1_13"       "SE1_14"      
## [121] "SE1_15"       "SE1_16"       "SE1_2"        "SE1_3"        "SE1_4"       
## [126] "SE1_5"        "SE1_6"        "SE1_7"        "SE1_8"        "SE1_9"       
## [131] "SE2_1"        "SE2_10"       "SE2_11"       "SE2_12"       "SE2_13"      
## [136] "SE2_14"       "SE2_15"       "SE2_16"       "SE2_2"        "SE2_3"       
## [141] "SE2_4"        "SE2_5"        "SE2_6"        "SE2_7"        "SE2_8"       
## [146] "SE2_9"        "ShirtColor"   "Spell"        "spell1"       "spell2"      
## [151] "Success"      "Success1"     "Team"         "team_2"       "Timeouts"    
## [156] "Timeouts1"    "VAR00001"     "VAR00002"
st.d  <- subset(stu.dat.df, select=c(Positive, Negative, Success, ShirtColor, Group))
describe(st.d)
## st.d 
## 
##  5  Variables      142  Observations
## ------------------------------------------------------------------------------------------
## Positive 
##       n missing  unique    Mean     .05     .10     .25     .50     .75     .90     .95 
##      79      63      13  0.1034 -0.8500 -0.5000 -0.3333  0.0000  0.5000  1.0000  1.0000 
## 
## -1 (4, 5%), -0.833333333333333 (1, 1%), -0.666666666666667 (2, 3%) 
## -0.5 (4, 5%), -0.333333333333333 (13, 16%), -0.166666666666667 (5, 6%) 
## 0 (15, 19%), 0.166666666666667 (7, 9%), 0.333333333333333 (7, 9%) 
## 0.5 (3, 4%), 0.666666666666667 (4, 5%), 0.833333333333333 (1, 1%) 
## 1 (13, 16%) 
## ------------------------------------------------------------------------------------------
## Negative 
##       n missing  unique    Mean 
##      78      64       5 -0.5641 
## 
##           -1 -0.5  0 0.5 1
## Frequency 45    6 21   4 2
## %         58    8 27   5 3
## ------------------------------------------------------------------------------------------
## Success 
##       n missing  unique 
##      84      58       7 
## 
##           Red Blue Bicolor Red/Blue Red/Bicolor Blue/Bicolor Three way tie
## Frequency  15   20      21        2           2            1            23
## %          18   24      25        2           2            1            27
## ------------------------------------------------------------------------------------------
## ShirtColor 
##       n missing  unique 
##     126      16       3 
## 
## Red (43, 34%), Blue (39, 31%), Bicolor (44, 35%) 
## ------------------------------------------------------------------------------------------
## Group 
##       n missing  unique 
##     142       0       3 
## 
## Control (41, 29%), Non-Verified (50, 35%), Verified (51, 36%) 
## ------------------------------------------------------------------------------------------

I’m not sure what I am looking at here.

summary(Positive ~ ShirtColor:Group, st.d, method="cross", fun=smean.sd)
## 
##  smean.sd by ShirtColor, Group 
## 
## +-------+
## |N      |
## |Missing|
## |Mean   |
## |SD     |
## +-------+
## +----------+--------+------------+--------+--------+
## |ShirtColor| Control|Non-Verified|Verified|   ALL  |
## +----------+--------+------------+--------+--------+
## |  Red     | 8      |   7        | 9      |24      |
## |          | 4      |   9        | 6      |19      |
## |          | 0.02083|   0.19048  |-0.09259| 0.02778|
## |          |0.7686  |  0.4947    |0.3017  |0.5376  |
## +----------+--------+------------+--------+--------+
## |  Blue    | 4      |  10        |11      |25      |
## |          | 4      |   6        | 4      |14      |
## |          | 0.04167|  -0.11667  | 0.30303| 0.09333|
## |          |0.3436  |  0.1933    |0.5100  |0.4197  |
## +----------+--------+------------+--------+--------+
## |  Bicolor |10      |   9        |11      |30      |
## |          | 4      |   4        | 6      |14      |
## |          | 0.11667|   0.18519  | 0.21212| 0.17222|
## |          |0.6576  |  0.7238    |0.7230  |0.6787  |
## +----------+--------+------------+--------+--------+
## |  NA      | 0      |   0        | 0      | 0      |
## |          | 7      |   5        | 4      |16      |
## |          |        |            |        |        |
## +----------+--------+------------+--------+--------+
## |  ALL     |22      |  26        |31      |79      |
## |          |19      |  24        |20      |63      |
## |          | 0.06818|   0.07051  | 0.15591| 0.10338|
## |          |0.6334  |  0.5125    |0.5593  |0.5606  |
## +----------+--------+------------+--------+--------+
summary(Negative ~ ShirtColor:Group, st.d, method="cross", fun=smean.sd)
## 
##  smean.sd by ShirtColor, Group 
## 
## +-------+
## |N      |
## |Missing|
## |Mean   |
## |SD     |
## +-------+
## +----------+-------+------------+--------+-------+
## |ShirtColor|Control|Non-Verified|Verified|  ALL  |
## +----------+-------+------------+--------+-------+
## |  Red     | 8     |    7       |  9     |24     |
## |          | 4     |    9       |  6     |19     |
## |          |-0.1875|   -0.7143  | -0.6667|-0.5208|
## |          |0.7530 |   0.4880   | 0.4330 |0.5985 |
## +----------+-------+------------+--------+-------+
## |  Blue    | 4     |   10       | 11     |25     |
## |          | 4     |    6       |  4     |14     |
## |          |-0.2500|   -0.6500  | -0.6364|-0.5800|
## |          |0.5000 |   0.5798   | 0.4523 |0.5140 |
## +----------+-------+------------+--------+-------+
## |  Bicolor | 9     |    9       | 11     |29     |
## |          | 5     |    4       |  6     |15     |
## |          |-0.6111|   -0.7778  | -0.4091|-0.5862|
## |          |0.6009 |   0.4410   | 0.7006 |0.5986 |
## +----------+-------+------------+--------+-------+
## |  NA      | 0     |    0       |  0     | 0     |
## |          | 7     |    5       |  4     |16     |
## |          |       |            |        |       |
## +----------+-------+------------+--------+-------+
## |  ALL     |21     |   26       | 31     |78     |
## |          |20     |   24       | 20     |64     |
## |          |-0.3810|   -0.7115  | -0.5645|-0.5641|
## |          |0.6501 |   0.4934   | 0.5438 |0.5661 |
## +----------+-------+------------+--------+-------+

So, I’m not clear about the models, either. Are these in the right ballpark? When I use lmerTest, it says that the models are not identifiable. I am having a hard time thinking about these models, so I am acting like and undergrad and just plugging and chugging. I probably plugged wrong.

Can you describe the model you are looking for a little more? This one allow the effect of group to be different for each ShirtColor, I believe.

Also, I didn’t try Success as a DV since it looks nominal. I must have missed something.

(p.lm <- lmer(Positive ~ Group + (Group | ShirtColor), st.d))
## Linear mixed model fit by REML ['lmerMod']
## Formula: Positive ~ Group + (Group | ShirtColor) 
##    Data: st.d 
## REML criterion at convergence: 138.6 
## Random effects:
##  Groups     Name              Std.Dev. Corr       
##  ShirtColor (Intercept)       1.23e-13            
##             GroupNon-Verified 1.13e-01  0.62      
##             GroupVerified     1.29e-01 -0.62 -1.00
##  Residual                     5.60e-01            
## Number of obs: 79, groups: ShirtColor, 3
## Fixed Effects:
##       (Intercept)  GroupNon-Verified      GroupVerified  
##            0.0682             0.0112             0.0822
summary(p.lm)
## Linear mixed model fit by REML ['lmerMod']
## Formula: Positive ~ Group + (Group | ShirtColor) 
##    Data: st.d 
## 
## REML criterion at convergence: 138.6 
## 
## Random effects:
##  Groups     Name              Variance Std.Dev. Corr       
##  ShirtColor (Intercept)       1.51e-26 1.23e-13            
##             GroupNon-Verified 1.27e-02 1.13e-01  0.62      
##             GroupVerified     1.66e-02 1.29e-01 -0.62 -1.00
##  Residual                     3.13e-01 5.60e-01            
## Number of obs: 79, groups: ShirtColor, 3
## 
## Fixed effects:
##                   Estimate Std. Error t value
## (Intercept)         0.0682     0.1194    0.57
## GroupNon-Verified   0.0112     0.1749    0.06
## GroupVerified       0.0822     0.1730    0.48
## 
## Correlation of Fixed Effects:
##             (Intr) GrpN-V
## GropNn-Vrfd -0.683       
## GroupVerifd -0.690  0.310
(n.lm <- lmer(Negative ~ Group + (Group | ShirtColor), st.d))
## Linear mixed model fit by REML ['lmerMod']
## Formula: Negative ~ Group + (Group | ShirtColor) 
##    Data: st.d 
## REML criterion at convergence: 135.3 
## Random effects:
##  Groups     Name              Std.Dev. Corr       
##  ShirtColor (Intercept)       0.00e+00            
##             GroupNon-Verified 3.31e-06   NaN      
##             GroupVerified     1.01e-05   NaN -0.16
##  Residual                     5.59e-01            
## Number of obs: 78, groups: ShirtColor, 3
## Fixed Effects:
##       (Intercept)  GroupNon-Verified      GroupVerified  
##            -0.381             -0.331             -0.184
summary(n.lm)
## Linear mixed model fit by REML ['lmerMod']
## Formula: Negative ~ Group + (Group | ShirtColor) 
##    Data: st.d 
## 
## REML criterion at convergence: 135.3 
## 
## Random effects:
##  Groups     Name              Variance Std.Dev. Corr       
##  ShirtColor (Intercept)       0.00e+00 0.00e+00            
##             GroupNon-Verified 1.10e-11 3.31e-06   NaN      
##             GroupVerified     1.03e-10 1.01e-05   NaN -0.16
##  Residual                     3.12e-01 5.59e-01            
## Number of obs: 78, groups: ShirtColor, 3
## 
## Fixed effects:
##                   Estimate Std. Error t value
## (Intercept)         -0.381      0.122   -3.12
## GroupNon-Verified   -0.331      0.164   -2.02
## GroupVerified       -0.184      0.158   -1.16
## 
## Correlation of Fixed Effects:
##             (Intr) GrpN-V
## GropNn-Vrfd -0.744       
## GroupVerifd -0.772  0.574