Question

(Aside from providing the results of the simulation or statistical tests, be sure to answer the questions – in bold.)

1. Many states and localities now collect data on traffic stops regarding the race of the driver. The initial concern was that Black drivers were being stopped more often. With more data in hand, attention has turned to other issues. For example, data from 2533 traffic stops in Cincinnati report the race of the driver (Black, White, or Other) and whether the traffic stop resulted in a search of the vehicle. Is there evidence that race is a factor in vehicle searches? Include your chi-square test calculations and null and alternative hypotheses.

	Black	White	Other	Total
Not Searched	787	594	27	1408
Searched	813	293	19	1125
Total	1600	887	46	2533

Answer 1

The hypothesis being tested is:

H0: race is not a factor in vehicle searches

Ha: race is a factor in vehicle searches

		Col 1	Col 2	Col 3	Total
Row 1	Observed	787	594	27	1408
	Expected	889.38	493.05	25.57	1408.00
	O - E	-102.38	100.95	1.43	0.00
	(O - E)² / E	11.79	20.67	0.08	32.53
Row 2	Observed	813	293	19	1125
	Expected	710.62	393.95	20.43	1125.00
	O - E	102.38	-100.95	-1.43	0.00
	(O - E)² / E	14.75	25.87	0.10	40.72
Total	Observed	1600	887	46	2533
	Expected	1600.00	887.00	46.00	2533.00
	O - E	0.00	0.00	0.00	0.00
	(O - E)² / E	26.54	46.54	0.18	73.25
		73.25	chi-square
		2	df
		1.24E-16	p-value

The p-value is 0.0000.

Since the p-value (0.0000) is less than the significance level (0.05), we can reject the null hypothesis.

Therefore, we can conclude that race is a factor in vehicle searches.