Chi-Square

Intro Statistics for Social Sciences (Professor April Garcia Peck)

Prepare: Watch the jamovi video lessons for Lesson 15. 

Dataset needed: jamovi Dataset - Lesson 15.omv

Assignment Prompt:

A health study was conducted to examine the effects of handwashing on illness among elementary school children. The researchers conducted their observations during the hours of 8 AM to 3 PM, Monday through Friday in December 2019. The researchers selected two classrooms for this study:

● One classroom was equipped with a sink and soap for handwashing. The teacher required students to wash their hands with soap and water after recess and before snack and lunch.

● One classroom did not have a sink or soap for handwashing.

The researchers also recorded how many students got sick with a cold or flu during the observation period. They want to answer the following questions:

● For the children who got sick with a cold or flu, was handwashing more common?

● Is there a relationship between handwashing and illness?

Use jamovi to find the answers to the items below:

1. Filter the dataset so that only “Sick” cases are selected. Run a Chi-Square Goodness of Fit test and select “Intervention” as the variable. What are the expected counts for both Handwashing and No Handwashing? (report to 2 decimal places) _________

2. What is the p-value for this Chi-Square Goodness of Fit test? (report to 3 decimal places) ______

3. What is your decision regarding H0 if alpha is .05? (Make sure you provide all conclusion statements!)____________________

4. Remove the filter from the dataset. Run a Chi-Square Test of Independence. Select “Outcome” as the Rows variable. Select “Intervention” as the Columns variable. What is the p-value for this test? (report to 3 decimal places) ______

5. What is your decision regarding H0 if alpha is .05? (Make sure you provide all conclusion statements!)_________________

6. What statistic should the researchers provide if there is a statistically significant relationship – the Phi Coefficient or Cramer’s V? ______

7. What is the strength of the association? (report to 2 decimal places) ______