---

title: “Week 6 Markdown” author: “Jasmine Moore” date: “2026-08-02” output: html_document

options(repos = c(CRAN = "http://cran.us.r-project.org"))
install.packages("rstatix")

## Installing package into 'C:/Users/Jasmine/AppData/Local/R/win-library/4.6'
## (as 'lib' is unspecified)

## package 'rstatix' successfully unpacked and MD5 sums checked
## 
## The downloaded binary packages are in
##  C:\Users\Jasmine\AppData\Local\Temp\RtmpaEzyhc\downloaded_packages

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(readxl)
A6Q1 <- read_excel("C:/Users/Jasmine/Desktop/AA521 Week 6/A6Q1.xlsx")

Before <- A6Q1$Before
After <- A6Q1$After
Differences <- After - Before
mean(Before, na.rm = TRUE)

## [1] 76.13299

hist(Differences,
            main = "Histogram of Different Scores",
            xlab = "Value",
            ylab = "Frequency",
            col = "blue",
            border = "black",
            breaks = 20)

#Histogram Difference Scores
#The difference scores look normally distributed.
#The data is roughly symmetrical.
#The data has a proper bell curve

  boxplot(Differences,
                   main = "Distribution of Score Differences (After - Before)",
                   ylab = "Difference in Scores",
                   col = "blue",
                   border = "darkblue")

#There is one dot outside the boxplot.
#The dot is past the whiskers.
#The dot is not very far away from the whiskers.
#Based on these findings, the boxplot is normal.

shapiro.test(Differences)

## 
##  Shapiro-Wilk normality test
## 
## data:  Differences
## W = 0.94757, p-value = 0.3318

#Shapiro-Wilk Difference Scores
#The data is normally distributed, (p = .3318).
 
t.test(Before, After, paired = TRUE, na.action = na.omit)

## 
##  Paired t-test
## 
## data:  Before and 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

wilcox.test(Before, After, paired = TRUE, na.action = na.omit)

## 
##  Wilcoxon signed rank exact test
## 
## data:  Before and After
## V = 148, p-value = 0.114
## alternative hypothesis: true location shift is not equal to 0

cohen.d(Before, After, paired = TRUE)

## 
## Cohen's d
## 
## d estimate: 0.6284306 (medium)
## 95 percent confidence interval:
##      lower      upper 
## -0.1035207  1.3603820

    df_long <- data.frame(
      id = rep(1:length(Before), 2),
      time = rep(c("Before", "After"), each = length(Before)),
      score = c(Before, After)
 )

wilcox_effsize(df_long, score ~ time, paired = TRUE)

## # A tibble: 1 × 7
##   .y.   group1 group2 effsize    n1    n2 magnitude
## * <chr> <chr>  <chr>    <dbl> <int> <int> <ord>    
## 1 score After  Before   0.359    20    20 moderate

#A Dependent T-Test was conducted to determine if there was a difference in weight before the diet versus after the diet.

#Before scores (M = 76.13, SD = 7.78) were not significantly different from after scores (M = 71.59, SD = 6.64), t(19) = 1.90, p > .05.

#The effect size is not reported.