Assignment 6 Question 2

library(readxl)
library(ggpubr)

## Loading required package: ggplot2

library(effsize)
library(rstatix)

## 
## Attaching package: 'rstatix'

## The following object is masked from 'package:stats':
## 
##     filter

library(tidyr)

A6Q2 <- read_excel("C:/Users/DeSheila Hatcher/OneDrive/AA 5221/Assignment 6/A6Q2.xlsx")

Before <- A6Q2$Before
After <- A6Q2$After

Differences <- After - Before

mean(Before, na.rm = TRUE)

## [1] 76.13299

median(Before, na.rm = TRUE)

## [1] 75.95988

sd(Before, na.rm = TRUE)

## [1] 7.781323

mean(After, na.rm = TRUE)

## [1] 57.17874

median(After, na.rm = TRUE)

## [1] 58.36459

sd(After, na.rm = TRUE)

## [1] 14.39364

hist(Differences,
     main = "Histogram of Difference Scores",
     xlab = "Difference in Weight",
     ylab = "Frequency",
     breaks = 20)

shapiro.test(Differences)

## 
##  Shapiro-Wilk normality test
## 
## data:  Differences
## W = 0.89142, p-value = 0.02856

wilcox.test(Before, After, paired = TRUE, exact = FALSE)

## 
##  Wilcoxon signed rank test with continuity correction
## 
## data:  Before and After
## V = 210, p-value = 9.569e-05
## alternative hypothesis: true location shift is not equal to 0

A6Q2_long <- A6Q2 %>%
  pivot_longer(
    cols = c(Before, After),
    names_to = "Time",
    values_to = "Weight"
  )

A6Q2_long %>%
  wilcox_effsize(Weight ~ Time, paired = TRUE)

## # A tibble: 1 × 7
##   .y.    group1 group2 effsize    n1    n2 magnitude
## * <chr>  <chr>  <chr>    <dbl> <int> <int> <ord>    
## 1 Weight After  Before   0.877    20    20 large

A Wilcoxon Signed-Rank Test was conducted to determine whether there was a difference in body weight before versus after participants followed the keto diet. Before scores (Mdn = 75.96) were significantly different from after scores (Mdn = 58.36), V = 210, p < .001. The effect size was large, r = .877.

Assignment 6 Question 2 – Keto Diet

DeSheila Hatcher

2026-09-26