# Koji Yatani's Course Webpage

### Site Tools

hcistats:poweranalysis

# Differences

This shows you the differences between two versions of the page.

 hcistats:poweranalysis [2014/03/29 02:19]Koji Yatani [Retrospective Power Analysis (not recommended)] hcistats:poweranalysis [2014/03/29 02:20] (current)Koji Yatani [Introduction] Both sides previous revision Previous revision 2014/03/29 02:20 Koji Yatani [Introduction] 2014/03/29 02:19 Koji Yatani [Retrospective Power Analysis (not recommended)] 2014/03/29 02:19 Koji Yatani [Retrospective Power Analysis (not recommended)] 2014/03/29 02:19 Koji Yatani created 2014/03/29 02:20 Koji Yatani [Introduction] 2014/03/29 02:19 Koji Yatani [Retrospective Power Analysis (not recommended)] 2014/03/29 02:19 Koji Yatani [Retrospective Power Analysis (not recommended)] 2014/03/29 02:19 Koji Yatani created Line 3: Line 3: \\ \\ =====Introduction===== =====Introduction===== + NHST can tell you how likely randomly sampled data would be like your data or even more extreme than it given that the null hypothesis (//e.g.//, there is no difference in the mean across the groups to compare) is true. As a standard threshold, we use 0.05, and we call this //alpha//. This means that if randomly sampled data can be like your data at lower than 5% change, you reject the null hypothesis (and claim that we observe a difference). Thus, if your p value is lower than //alpha//, we say that you have a significant result. NHST can tell you how likely randomly sampled data would be like your data or even more extreme than it given that the null hypothesis (//e.g.//, there is no difference in the mean across the groups to compare) is true. As a standard threshold, we use 0.05, and we call this //alpha//. This means that if randomly sampled data can be like your data at lower than 5% change, you reject the null hypothesis (and claim that we observe a difference). Thus, if your p value is lower than //alpha//, we say that you have a significant result. Line 11: Line 11: - ^^Reject the null hypothesis^Fail to reject the null hypothesis^ + ^ ^Reject the null hypothesis^Fail to reject the null hypothesis^ |The null hypothesis is true.|**Type I error** (false positive)|True negative| |The null hypothesis is true.|**Type I error** (false positive)|True negative| |The null hypothesis is false.|True positive|**Type II error** (false negative)| |The null hypothesis is false.|True positive|**Type II error** (false negative)| 