Assignment6Q1

#Is there a mean difference in body weight (kg) before versus after all participants tried the low calorie diet?

library(readxl)
library(ggpubr)

## Loading required package: ggplot2

library(dplyr)

## 
## Attaching package: 'dplyr'

## The following objects are masked from 'package:stats':
## 
##     filter, lag

## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union

library(effectsize)
library(effsize)
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

A6Q1 <- read_excel("~/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 Difference Body Weight"),
     xlab = "Value",
     ylab = "Frequency",
     col = "blue",
     border = "black",
     breaks = 20)

Histogram of Difference Body Weight The difference in body weight look abnormally distributed. The data is negatively skewed skewed. The data does not have a proper bell curve.

boxplot(Differences,
        main = "Distribution of Body Weight (After - Before)",
        ylab = "Difference in Body Weight",
        col = "blue",
        boreder = "darkblue")

Boxplot= There are dots outside the boxplot. The dots are close to the whiskers. The dots are 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 In Body Weight 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 Body Weight before Low Calorie diet versus after Low Calorie diet. Before Low Calorie diet (M = 76.13, SD = 7.79) were not significantly different from after Low Calorie diet (M = 71.59, SD = 6.64), t(19) = 1.9, p = 0.072.