19 Areport released by the Pew Internet American Life Proje

19. Areport released by the Pew Internet & American Life Project entitled The Internet & Consumer Choice focused on current online issues. Respondents were asked to indicate their level of agreement 1.3strongly agree to 4 3 strongly disagree) with a variety of statements including \"I don\'t like giving my credit card number or personal information online.\" A part of the data set was used to determine whether the type of community in which the individual resides (Urban, Suburban, or Rural) affected responses. Here are the results in the form of a partially completed Analysis of Variance table Sum of Mean Source DF Squares Square F-ratio P-value Community 2 6.615 Error 183 96.998 Total 185 103.613 a. Is this an experimental or observational study? Explain. b. Is this a prospective or retrospective study? Explain. c. State the null and alternative hypothesis. d. Calculate the F-statistic. e. Calculate the P-value. State your conclusion. Can a causal link be established? Explain.

Solution

a) This is an observational study. Experimental study means trying a new product or method. But here existing method is tried with results. So observational

b) Prospective study as for future development this is done.

c. H0: Responses are independent of types of communities

   Ha: Responses are not independent of types of communities

Two tailed test.

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d) For F statistic complete the table as

As p <0.01, at 1% significance level, H0 is rejected.

i.e. Responses are not independent of types of communities

Hence a causal link can be established, as the variables are dependent.

Source	DF	SS	MS	F	p
Commu.	2	6.615	3.3075	6.240051	0.00239
Error	183	96.998	0.530044