Talk:Z-test

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Hi all,

in the line "a mean score of 96 is -2.47 standard deviation units from the population mean", shouldn't it say "standard error units"? I'm not sure about this, so if you know for sure, please change or don't.

Regards WikiBasti 12:16, 25 November 2005 (UTC)

This sentence in the article: "What this tells us is that 49.32% plus 50% or 99.32% of the students who took the test scored better than did the fifth grade students in our sample" is misleading. It's not true that 99.32% of all students do better: what's true is that 99.32% of the time, a randomly selected group of 55 students have a higher average score than these 55 students had. MvH Jan 16, 2006.

[edit] Two-sided test

I think it should be clarified at the bottom of this article that this is a two-sided test as opposed to a one-sided test.

[edit] Simple random sample

The article states that the sample must be a simple random sample from the population, but I can't make sense of this. Isn't this the null hypothesis, and consequently, isn't the test only meaningful if the sample is NOT random? The test is used to see if the sample that you drew from the population behaves like a simple random sample...it's only interesting if it doesn't -anon