Statistics > Confidence Intervals > 2-Population Proportion Statistics > Confidence Intervals > 2-Population Proportion This utility computes confidence intervals for the difference of two population proportions. The confidence interval estimate of p1 - p2 is: where the margin of error E is given by , is the sample proportion, and . Dialog Inputs The sample data of the population must be of only two categories. They can be inputted in one of three ways: Samples in one column: The population labels of samples are in one column of the Datasheet, and the individual samples are in another column. Samples in two columns: The samples of the two population are in two separate columns. Summarized sample data: The number of events and the number of trials of each of the two populations are provided (instead of individual sample values). The confidence level must be between 0 and 1. For example, enter 0.95 for a 95% confidence level.