A6Q2

library(readxl)
library(ggpubr)

## Loading required package: ggplot2

library(effectsize)
library(rstatix)

## 
## Attaching package: 'rstatix'

## The following objects are masked from 'package:effectsize':
## 
##     cohens_d, eta_squared

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

A6Q2 <- read_excel("/Users/tulsiheerekar/Downloads/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 = "Value",
                        ylab = "Frequency",
                        col = "violet",
                        border = "black",
                        breaks = 20)

                   #Histogram of Difference Scores
                   #The difference scores look abnormally distributed.
                   #The data is negatively skewed.
                   #The data does not have a proper bell curve.
                   
                                                 boxplot(Differences,
                                                         main = "Distribution of Score Differences (After - Before)",
                                                         ylab = "Difference in Scores",
                                                         col = "violet",
                                                         border = "black")

                                                 #Interpret the Boxplots
                                                 #There is one dot outside the boxplot.
                                                 #The dot is not close to the whiskers.
                                                 #The dot is  very far away from the whiskers.
                                                 #Based on these findings, the boxplot is not normal.
                                                 #Shapiro-Wilk Tests (Normality Check #3)
                                                                     shapiro.test(Differences)

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

                                                                     #Interpret the Shapiro-Wilk Test
                                                                     #Shapiro-Wilk Difference Scores
                                                                     #The data is abnormally distributed, (p = .023)
                                                                     #Conduct the Wilcoxon Signed Rank since the data was ABNORMAL to determine if there was a difference before versus after
                                                                     
                                                                     wilcox.test(Before, After, paired = TRUE, na.action = na.omit)

## 
##  Wilcoxon signed rank exact test
## 
## data:  Before and After
## V = 210, p-value = 1.907e-06
## alternative hypothesis: true location shift is not equal to 0

                                                                     #Calculate Effect Size for Wilcoxon Signed Rank
                                                                     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   0.877    20    20 large

                                                                     #Report the Wilcoxon Signed Rank
                                                                     #A Wilcoxon Signed-Rank Test was conducted to determine if there was a difference in OutcomeVariable before Independent Variable versus after Independent Variable.
                                                                     #Before scores (Mdn = 76) were significantly different from after scores (Mdn = 58.37), V = 210, p < .001.
                                                                     #The effect size was large, r = .88.