1 / 34

340 likes | 451 Vues

Week 5. POWER AND SAMPLE SIZE. Terminology : Normal Samples. Power is the probability of rejecting a false null hypothesis. Power should be close to one. N1 and N2 are the number of items sampled from each population. To conserve resources, they should be small.

Télécharger la présentation
## Week 5

**An Image/Link below is provided (as is) to download presentation**
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.
Content is provided to you AS IS for your information and personal use only.
Download presentation by click this link.
While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

**Week 5**POWER AND SAMPLE SIZE**Terminology: Normal Samples**• Power is the probability of rejecting a false null hypothesis. Power should be close to one. • N1 and N2 are the number of items sampled from each population. To conserve resources, they should be small. • Alpha is the probability of rejecting a true null hypothesis. It should be small. • Beta is the probability of accepting a false null hypothesis. It should be small. • Mean1 is the mean of populations 1 and 2 under the null hypothesis of equality. • Mean2 is the mean of population 2 under the alternative hypothesis. The mean of population 1 is unchanged. • S1 and S2 are the population standard deviations. They represent the variability in the populations.**Terminology: Counts/Proportions**• Power is the probability of rejecting a false null hypothesis. It should be close to one. • Ni is the size of the sample drawn from the ith population. • Allocation Ratio is N2/N1 so that N2 = N1 x R. • Alpha is the probability of rejecting a true null hypothesis. It should be small. • Beta is the probability of accepting a false null hypothesis. It should be small. • P1 is the proportion for group one. • P2 is the proportion for group two under the alternative hypothesis. • Odds Ratio is [P2/(1-P2)] / [P1/(1-P1)].**SPSS module SAMPLEPOWER**• SigmaStat (SPSS product) • PASS (NCSS product) • SPLUS (Insightful product) SPSS: • www.spss.com/spssbi/samplepower/ • www.spssscience.com/SigmaStat/index.cfm NCSS: www.ncss.com/pass.html INSIGHTFUL: www.insightful.com/products/

More Related