Question

*Please do this question in Minitab*

The Response Rate Data

A study was designed to see if a mail survey’s response rate could be improved by contacting the potential respondents before they received the survey. One group of individuals received a preliminary letter about the survey, the second group was phoned, and the third group received no preliminary contact. The table below gives the counts of responses (yes/no) two weeks after the survey was mailed. (ref: Moore & McCabe, Intro Practice of Statistics, third edition, Freeman)

	Intervention
Response?	Letter	Phone Call	None
Yes	171	146	118
No	220	68	455
Total	391	214	573

Did the intervention make a difference? If so, what was the difference?

Answer 1

		c1	c2	c3	sum
	r1	171	146	118	435
	r2	220	68	455	743
	sum	391	214	573	1178
	Eij	1	2	3
expected	1	144.3846	79.02377	211.5917
	2	246.6154	134.9762	361.4083
	0i	171	146	118	220	68	455
	Ei	144.3846	79.02377	211.5917	246.6154	134.9762	361.4083192
								sum
	(Oi-Ei)^2/Ei	4.906219	56.7654	41.39767	2.872416	33.23411	24.23685968	163.4127
							critical value	5.991465
							p-value	3.28E-36

df = 2

TS = 163.41

critical value = 5.99 for alpha = 0.05

since TS > critical value

we reject the null hypothesis