week6

#install.packages("rstatix")
#install.packages("effectsize")
library(readxl)
library(ggpubr)

## Loading required package: ggplot2

library(rstatix)

## 
## Attaching package: 'rstatix'

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

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

Before <- (A6Q1$Before)
After <- (A6Q1$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] 71.58994

median(After, na.rm = TRUE)

## [1] 70.88045

sd(After, na.rm = TRUE)

## [1] 6.639509

hist(Differences,
     main = "Histogram of Body Weight Differences (After - Before)",
     xlab = "Weight Difference (kg)",
     ylab = "Number of Participants",
     col = "blue",
     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 = "Boxplot of Body Weight Differences (After - Before)",
        ylab = "Weight Difference (kg)",
        col = "blue",
        border = "darkblue")

#Boxplot
#There [are] dots outside the boxplot.
#The dots [are not] close to the whiskers.
#The dots [are] 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 = .0.3318).
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

#A Dependent T-Test was conducted to determine if there was a difference in OutcomeVariable before Independent Variable versus after Independent Variable.
#Before scores (M = 76.13, SD = 7.78) were [not significantly] different from after scores (M = 71.58, SD = 6.63), t(19) = 1.902, p > .05.