Chapter 9 - Day 8
Students Struggled With…
Remembering to use the combined sample proportion when checking the large counts condition and calculating standard deviation.
Adjusting the alpha level when asked how a confidence interval is consistent with the results of a one-sided test.
When we teach students how to structure their problems, make sure for the "statistic" step at the very beginning to have them writing the sample proportion 1, sample proportion 2, and the combined sample proportion. This should help them remember that we will be needing to use it instead.
Help the students to visualize this! When you do a confidence interval problem, shade the area that we believe the true parameter is in. Color the tails in a different color to make the students see the region a two-sided hypothesis test is assessing. Therefore - a 90% confidence interval would have 10% leftover in the tails - or 5% on each side. For a one -sided significance test, we need to be using alpha = .05.