Exercise 4.38 on page 235 describes a study to investigate whether a recorded phone call is more effective than a flyer in persuading voters to vote for a particular candidate. The response variable is the proportion of voters planning to vote for the candidate, with p_cand p_f representing the proportions for the two methods (receiving a phone call and receiving a flyer, respectively.) The sample statistic of interest is D = pÌ‚_cˆ’ pÌ‚_f. We are testing H₀: p_c= p_fvs H_a: p_c> p_f. A randomization distribution for this test is shown in Figure 4.18.

Figure 4.18

(a) Sketch a smooth curve that roughly approximates the distribution in Figure 4.18 and shade in the proportion of the area corresponding to the p-value for the sample statistic D = 0.3.
(b) Four possible sample statistics are given, along with four possible p-values. Match the statistics with the p-values:
Statistics : 0.1, 0.3, 0.5, 0.7
P-values : 0.012, 0.001, 0.365, 0.085
(c) Interpret the p-value 0.001 in terms of the probability of the results happening by random chance.
(d) Of the four p-values given in part (b), which provides the strongest evidence that a phone call is more effective?

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120 100 - 80 60 40 20 0.2 -0.6 -0.4 -0.2 0.0 0.4 0.6 DIfference Frequency