Open the Installed Packages

library(readxl) 
library(ggplot2) 
library(rcompanion)

Import and Name Dataset

DatasetA2 <- read_excel("C:/Users/yenug/OneDrive/Documents/Assignment 5/DatasetA2.xlsx")

Create a Frequency Table

table(DatasetA2$FavoriteDrink)
## 
## Coffee   Soda    Tea  Water 
##     26     29     28     17

Create a Bar Chart

ggplot(DatasetA2, aes(x = FavoriteDrink, fill = FavoriteDrink)) +
  geom_bar() +
  labs(
    x = "FavoriteDrink",
    y = "Frequency",
    title = "Student Beverage Preferences"
  ) +
  theme(
    text = element_text(size = 14),       
    axis.title = element_text(size = 14),  
    axis.text = element_text(size = 14),  
    plot.title = element_text(size = 14)
  )

Conduct the Chi-Square Goodness-of-Fit Test

observed <- c(26, 29, 28, 17) 
expected <- c(0.25, 0.25, 0.25, 0.25)
chisq.test(x = observed, p = expected)
## 
##  Chi-squared test for given probabilities
## 
## data:  observed
## X-squared = 3.6, df = 3, p-value = 0.308

Interpret and Report the Results

A chi-square goodness-of-fit test indicated that the observed frequencies were not different from the expected frequencies, χ²(2) = 3.6, p = 0.308. Cohen’s W effect size was not calculated as the P-value is not statistically significant.

library(rmarkdown)