Chi Square Test for Goodness of Fit

p ,5,8

 Measure the distribution of a proportions within a single population.  Goodness of Fit: does specified population distribution seem valid  Homogeneity: compare two or more population proportions

BrownRedYellowOrangeBlueGreen

BrownRedYellowOrangeBlueGreenTotal Observed Expected (O-E) 2 /E

DayObserved Count Expected Count (O-E)2/E Sun20 Mon133 Tues126 Wed159 Thurs136 Fri113 Sat12

 Are you more likely to have a motor vehicle collision when using a cell phone? A study of 699 drivers who were suing a cell phone when they were involved in a collision examined this question. The drivers made 26,798 cell phone calls during a 14-month period. Each of 699 collisions was classified in various ways. Here are the counts for each day of the week.

DaySunMonTuesWedThursFriSatTotal Number Ho: p Sun = p mon = p Tues = ……P sat = 1/7 Ha: At least one of the proportions differs from the stated value

 Market researchers know that background music an influence the mood and purchasing behavior of customers. One study in a supermarket in Northern Ireland compared three treatments: no music, French accordion music, and Italian string music. Under each condition, the researchers recorded the numbers of bottles of French, Italian, and other wine purchased. Here is a table that summarizes the data.   Populations:  Population 1: bottles of wine sold while no music is playing Population 2: bottles of wine sold while French music is playing  Population 3 : bottles of wine sold while Italian music is playing 

 Ho: The proportions of each wine type sold are the same in all three populations  Ha: At least one proportion different

Wine/musicNoneFrenchItalianTotal French Italian Other Total Observed Data Expected Data Wine/musicNoneFrenchItalianTotal French Italian Other Total