Confidence Interval on the Difference Between Proportions (2 of 4)

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Therefore the proportions who solve the problem are 0.65 for the psychology majors (p1) and 0.41 for the physics majors (p2). The goal of the experiment is to estimate the difference between the proportion of psychology majors in the population that can solve the problem (π1) and the proportion of physics majors in the population that can solve it ( π2). The statistic p1 - p2 is used as an estimate of π1 - π2. In this experiment, the estimated value of π1 - π2 is 0.65 - 0.41 = 0.24.

To compute the confidence interval, the standard error of p1- p2 is needed. The standard error is:

The estimated standard error is:

= 0.067
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