Load Packages

library(readxl)

Import Data

A6Q2 <- read_excel("C:/Users/wmacklin/Downloads/A6Q2.xlsx")

Test for Normality

difference <- A6Q2$After - A6Q2$Before
shapiro.test(difference)
## 
##  Shapiro-Wilk normality test
## 
## data:  difference
## W = 0.89142, p-value = 0.02856

Wilcoxon Signed-Rank Test

wilcox.test(A6Q2$Before,
            A6Q2$After,
            paired = TRUE)
## 
##  Wilcoxon signed rank exact test
## 
## data:  A6Q2$Before and A6Q2$After
## V = 210, p-value = 1.907e-06
## alternative hypothesis: true location shift is not equal to 0

Boxplot

boxplot(A6Q2$Before,
        A6Q2$After,
        names = c("Before", "After"),
        main = "Body Weight Before and After Keto Diet",
        ylab = "Body Weight (kg)")

Interpretation

A Shapiro-Wilk test indicated that the differences in body weight were not normally distributed (W = 0.89142, p = 0.02856). Therefore, a Wilcoxon signed-rank test was conducted. The results showed a statistically significant difference in body weight before and after participants followed the keto diet, V = 210, p < .001. These findings indicate that body weight changed significantly after participants tried the keto diet.