PSYCH 2220H Lecture Notes - Lecture 9: Null Hypothesis, Standard Error, Standard Deviation

• School: Ohio State University
• Department: Psychology
• Course: PSYCH 2220H
• Professor: Cravens- Brown Lisa Marie

Document Summary

Chapter 9: the single sample t-test: the problem of variance, we usually do not know . A. 1: have to estimate using our sample data, must correct the formula to estimate the population thus, 2 forms of standard deviation. Estimator: using sd of sample to estimate . Correcting the formula to estimate : descriptive version. Always trying to estimate the parameter (greek letters) using sample data. Using (n-1) for denominator makes s2 = unbiased (over the long run) S is larger b/c dividing by smaller number. Mistake b/c more likely to reject null hypothesis with. Example: murder rate in usa: 4. 5/100,000, murder rate in midwest: 3. 62, s=1. 79, step 1. May not be able to generalize to remainder of country. Quite robust to violations of assumptions: step 2. There is no difference in murder rate between usa and. M = all = 4. 5 s = 1. 79 sm = 0. 5178.