# GGR270H1 Final: Week 11 Study Notes

## Document Summary

Ggr 270 lecture 11 november 24, 2010. decision to reject or fail to reject h0 is made by comparing the test statistic to a critical value of z or t. but, different significance levels may lead to different conclusions. To avoid ambiguity, some researchers prefer to use a variable level of significance p value. smallest value of a for which the h0 can be rejected. actual risk of committing type 1 error. In comparing 2 samples, if the sample means are significantly different, can conclude they were drawn from different populations. must examine difference in sample means: if sample difference is large, likely conclusion is the population means are different. need to know variances: we end up using 2 approaches according to whether we believe the variances are equal or now. 2 sample means test requires that we make a decision on whether or not to pool sample variances.