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CHI-SQUARE TEST OF INDEPENDENCE OVERVIEW

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PURPOSE

To test if there is an association between two categorical variables.

NOTES

Normality does not apply to Chi-Square tests because data is only categorical.

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HYPOTHESES

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NULL HYPOTHESIS

There is no association between the two categorical variables.

ALTERNATE HYPOTHESIS

There is an association between the two categorical variables.

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IMPORT EXCEL FILE CODE

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PURPOSE OF THIS CODE

Imports your Excel dataset automatically into R Studio.

You need to import your dataset every time you want to analyze your data in R Studio.

INSTALL REQUIRED PACKAGE

The package only needs to be installed once.

The code for this task is provided below. Remove the hashtag below to convert the note into code.

options(repos = c(CRAN = "https://cloud.r-project.org"))
install.packages("readxl")
## Installing package into 'C:/Users/manit/AppData/Local/R/win-library/4.5'
## (as 'lib' is unspecified)
## package 'readxl' successfully unpacked and MD5 sums checked
## 
## The downloaded binary packages are in
##  C:\Users\manit\AppData\Local\Temp\RtmpmkBKDy\downloaded_packages

LOAD THE PACKAGE

You must always reload the package you want to use.

The code for this task is provided below. Remove the hashtag below to convert the note into code.

library(readxl)

IMPORT THE EXCEL FILE INTO R STUDIO

Download the Excel file from One Drive and save it to your desktop.

Right-click the Excel file and click “Copy as path” from the menu.

In R Studio, replace the example path below with your actual path.

Replace backslashes  with forward slashes / or double them //:

✘ WRONG “C:.xlsx”

✔ CORRECT “C:/Users/Joseph/Desktop/mydata.xlsx”

✔ CORRECT “C:\Users\Joseph\Desktop\mydata.xlsx”

Replace “dataset” with the name of your excel data (without the .xlsx)

An example of the code for this task is provided below.

You can edit the code below and remove the hashtag to use the code below.

dataset <- read_excel("C:/Users/manit/Downloads/RQ2.xlsx")

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VISUALLY DISPLAY THE DATA

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PURPOSE

Visually display the data.

A frequency table can be used instead of a bar graph to visually display the data.

CREATE A FREQUENCY TABLE

Also called a “contingency table” for Chi-Square Test of Independence.

Replace “dataset” with the name of your dataset (without the .xlsx)

Replace “Variable1” with the R code name of your first variable

Replace “Variable2” with the R code name of your second variable

Remove the hashtag to use the code.

contingencytable <- table(dataset$Parent, dataset$Preferred_Design)
print(contingencytable)
##         
##           A  B
##   Father 21 29
##   Mother 31 19

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CHI-SQUARE TEST OF INDEPENDENCE CODE

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PURPOSE

Determine if the null or alternate hypothesis was supported.

CONDUCT THE TEST

Do NOT edit the code.

Remove the hashtags to use the code.

chisq_indep <- chisq.test(contingencytable)
print(chisq_indep)
## 
##  Pearson's Chi-squared test with Yates' continuity correction
## 
## data:  contingencytable
## X-squared = 3.2452, df = 1, p-value = 0.07163

DETERMINE STATISTICAL SIGNIFICANCE

If results were statistically significant (p < .05), continue to the effect size section below.

If results were NOT statistically significant (p > .05), do NOT calculate the effect size.

Instead, skip to the reporting section below.

NOTE: Getting results that are not statistically significant does NOT mean you switch to a different test.

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RESEARCH REPORT ON RESULTS

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A Chi-Square Test of Independence was conducted to examine the association between parent (Father, mother) and design preference (Design A, design B) among 100 participants. There was not statistically significant association between parent and design preference, χ²(1, N = 100) = 3.2452, 3.2452 (p > .05). Hence effect size is un-needed