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### Course: AP®︎/College Statistics>Unit 10

Lesson 5: Carrying out a test for a population proportion

# Calculating a z statistic in a test about a proportion

Calculating a z statistic in a one-sample z test about a proportion.

## Want to join the conversation?

• It was never explained why z is the correct test statistic for this significance test. I imagine it isn't always the "correct test statistic" and would have appreciated an explanation of what the other choices would be and why. And if it is indeed the only one, then why is that. It would go a long way as to understanding why he did what he did here.

Thank you.

ETA: I googled test statistic and found there are 4 main ones, Z-test, T-test, ANOVA and Chi-Square Test. I didn't realize these were how the test statistic were used/found.
• 1 anf the z score of the twenty seven of the p hat proportion of the tur means
(1 vote)
• Duno why he stopped in the middle. This is the most important video to explain the significance test in action
• Shouldn't we be taking the standard deviation of the actual distribution rather than the standard deviation of the sample distribution?

Are we assuming they are approximately the same?
• The name test statistic seems a little confusing. I though, they asked about which population statistic the test is dealing with
(1 vote)
• I have the same problem with questions being vague like that, but in real world application, you would have to figure out for yourself what is the most proper test statistic for your data.

Generally you would use:
Z-test and Chi-squared test for categorical variables (counts/proportions)
T-test/ANOVA for numerical variables (averages/means)
• square rout from (P(1-P) divided on n) - isn't it the standard deviation of the population?! how can we use it as if it were the standard deviation of the sampling distribution?