Test of Independence

Test of Independence

The chi squared test statistic and test procedure can also be used to investigate association between 2 categorical variables in a single population.

The question of interest is often whether knowledge of one variable’s value provides any information about the value of the other variable – in other words, are the 2 variables independent?

Independent

Knowledge of one value does not provide information about another.

Very similar to Test of Homogeneity

Same test statistic Same way to figure the expected value Same way to find the degrees of freedom Same way of putting it in the matrices and

using the calculator. Same Assumptions

Differences

State in context of the problem

Assumptions Random samples Cells 5

: the 2 variables are independent

: the 2 variables are not independento

A

H

H

A sociologist wishes to see whether the number of years of college a person has completed is related to his or her place of residence. A random sample of 70 people is selected and classified as shown. Using a 5% significance level, can the sociologist conclude that the years of college education are dependent on the person’s location?

No College 4 yr deg Advanced

Urban 15 12 8

Suburban 8 15 9

Rural 6 8 7

A researcher wishes to determine whether there is a relationship between the gender of an individual and the amount of alcohol consumed. Use α = 0.01

Low Moderate High

Male 10 9 8

Female 13 16 12

Survey Questions

Each Group is to make a survey question that will generate data for each type of Chi-square Test.

Homework

Page 659 (20, 24, 25, 30, 32) Test for Homogeneity are mixed in with test of

independence!