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

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 College4 yr degAdvanced Urban15128 Suburban8159 Rural687

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 LowModerateHigh Male1098 Female131612

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!