Statistics for Business: Decision Making and Analysis, 3rd Edition

18.1 Chi-Squared Tests

Table 18.1 summarizes purchases at Amazon made by a sample of 555 visitors of varying income who bought either a camera or a mobile phone (but not both).

Table 18.1 Contingency table of purchase category versus household income.

Household Income					Total
Less than $25,000	$25,000 to $49,999	$50,000 to $74,999	$75,000 to $99,999	$100,000 or more
Purchase Category	Camera	26	38	76	57	50	247
	Phone	72	76	73	34	53	308
Total		98	114	149	91	103	555

The association evident in this contingency table suggests that income and choice are dependent. Households with lower incomes are more likely to purchase a phone, whereas higher-income households are more likely to purchase cameras. Almost 3/4 of those with estimated ...