PSY201 9.20.13 To Post

01 a researcher is interested in the eect of

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Unformatted text preview: n exam will improve students’ performance on the exam. She predicts that students who access review materials will do berer than students who do not access review materials. 10 9/19/13   As researchers, we open have a predicIon about a specific direcIon of effects. So, you would expect that we would open be using one ­tailed tests…   In prac(ce, however, we almost always use two ­tailed tests.   If we happen to find the opposite of what was predicted, then the two ­tailed test allows us to accept our data as meaningful and staIsIcally significant, and report on the findings.   If we used a one ­tailed test, and then found the opposite, we cannot reject the null hypothesis. (womp womp)   Unless the author specifically states otherwise, you can assume that psychology research papers used two ­tailed tests. Divide up your significance between the tails. Instead of .05 in one tail, you have .025 in both tails. What does this do to your criIcal values? Divide up your significance between the tails. Instead of .05 in one tail, you have .025 in both tails. What does this do to your criIcal values? 11 9/19/13 We have been focusing on a .05 level of significance (which is .025 in each tail in a two ­tailed test)… What about a more stringent level, sekng our p ­value < .01?   A researcher is interested in the effect of environmental condiIons on the quality of sleep. In parIcular, the research wants to examine whether living in a polluted region has an effect on individuals’ amount of sleep.   A randomly selected person from the polluted region sleeps an average of 10.2 hours per night.   Using a two ­tailed test at the .05 significance lev...
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