When surveys are administered, it is hoped that the respondents give accurate answers. Does the mode of survey delivery affect this? American researchers investigated this question (Schober et al., 2015). They had 634 people agree to be interviewed on an iPhone and they were randomly assigned one of the four interview modes (human voice, human text, automated voice, automated text). One question that was asked was whether they exercise less than once per week on a typical week (an example of a question in which a yes would be considered socially undesirable). The summarized data on the answers to this question are shown in the Exercise 8.1.30 table. 

a. State the hypotheses. 

b. Calculate the conditional proportions of those answering “yes” in each of the different interview modes. 

c. Calculate the Mean Group Diff. 

d. Use the Multiple Proportions applet to confirm calculation of the Mean Group Diff and to find the corresponding p-value. 

e. State your conclusion in the context of the research question. Include statements of generalization and causation.

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Exercise? Yes No Total Human text 34 124 158 Automated text 46 111 157 Human voice Automated voice 21 139 160 20 139 159 Total 121 513 634