In performing chi-square goodness fit test for a normal distribution,a researcher wants to make sure that all of the expected cell frequencies are at least five.The sample is divided into 7 intervals.The second through the sixth interval all have expected cell frequencies of at least five.The first and the last intervals have expected cell frequencies of 1.5 each.After adjusting the number of intervals,degrees of freedom for the chi-square statistic is ____.
A)2
B)3
C)5
D)7

Question

Quizplus · Accepted Answer

The degrees of freedom for a chi-square goodness-of-fit test is equal to the number of intervals minus 1. In this case, the researcher has 7 intervals, but the first and last intervals have expected cell frequencies of less than 5, so they are combined into one interval. This leaves the researcher with 6 intervals, and the degrees of freedom is 6 - 1 = 5.

In Performing Chi-Square Goodness Fit Test for a Normal Distribution,a