Research Question

Is there a mean difference in body weight (kg) before versus after all participants tried the low-calorie diet?

Statistical Test Selection

A paired-samples t-test was selected because the same participants were measured before and after trying the low-calorie diet. Therefore, the two measurements are dependent.

Descriptive Statistics

The mean body weight before the low-calorie diet was 76.13 kg (SD = 7.78), while the mean body weight after the low-calorie diet was 71.59 kg (SD = 6.64).

Paired-Samples T-Test

library(readxl)

A6Q1 <- read_excel("C:/Users/wmacklin/Downloads/A6Q1.xlsx")

t.test(A6Q1$Before,
       A6Q1$After,
       paired = TRUE)
## 
##  Paired t-test
## 
## data:  A6Q1$Before and A6Q1$After
## t = 1.902, df = 19, p-value = 0.07245
## alternative hypothesis: true mean difference is not equal to 0
## 95 percent confidence interval:
##  -0.4563808  9.5424763
## sample estimates:
## mean difference 
##        4.543048

Results and Conclusion

A paired-samples t-test was conducted to determine whether there was a statistically significant mean difference in body weight before versus after participants tried the low-calorie diet. The results were not statistically significant, t(19) = 1.90, p = .072. Although participants weighed an average of 4.54 kg more before the diet than after the diet, there was insufficient evidence to conclude that the low-calorie diet resulted in a statistically significant change in body weight.