上午—样本含量的估计 MPH 1.ppt

SAS SAS POWER AND SAMPLE SIZE SAS POWER AND SAMPLE SIZE POWER ANALYSIS AND SAMPLE SIZE (PASS) PASS PASS Two Independent Proportions (Null Case) Power Analysis Page/Date/Time 1 2012/10/24 23:12:01 Numeric Results of Tests Based on the Difference: P1 - P2 H0: P1-P2=0. H1: P1-P2=D10. Test Statistic: Z test with pooled variance Sample Sample Prop|H1 Prop Size Size Grp 1 or Grp 2 or Diff Diff Grp 1 Grp 2 Trtmnt Control if H0 if H1 Target Actual Power N1 N2 P1 P2 D0 D1 Alpha Alpha Beta 0.8128 39 39 0.8000 0.5000 0.0000 0.3000 0.0500 0.0536 0.1872 Note: exact results based on the binomial were only calculated when both N1 and N2 were less than 100. References ……. Report Definitions Power is the probability of rejecting a false null hypothesis. It should be close to one. N1 and N2 are the sizes of the samples drawn from the corresponding populations. P1 is the proportion for group one under H1. This is the treatment or experimental group. P2 is the proportion for group two. This is the standard, reference, or control group Target Alpha is the probability of rejecting a true null hypothesis that was desired. Actual Alpha is the value of alpha that is actually achieved. Beta is the probability of accepting a false null hypothesis. Summary Statements Group sample sizes of 39 in group one and 39 in group two achieve 81% power to detect a difference between the group proportions of 0.3000. The proportion in group one (the treatment group) is assumed to be 0.5000 under the null hypothesis and 0.8000 under the alternative hypothesis. The proportion in group two (the control group) is 0.5000. The test statistic used is the two-sided Z test with pooled variance. The significance level of the test was targeted at 0.0500. The significance level actually achieved by this design is 0.0536. PASS求POWER Two Independent Proportions (Null Case) Power Analysis Page/Date/Time 1 2012/10/24 23:14:53 Numeric Results of Tests Based on the Odds Ratio: O1 / O2 H0: O1/O2=1.