STATS 250 Study Guide - Final Guide: Standard Deviation, Correlation And Dependence, Total Variation

• School: U of M
• Department: Statistics
• Course: STATS 250
• Professor: Brenda Gunderson

Document Summary

Parameter of interest: difference in population means 1 - 2. Difference in sample means: x-bar 1 - x-bar 2 (x1 - x2) 1 = population mean amount of time watching tv by millennials. If sample size at least 25; normality not necessary. of n 1 -1 or n 2 -1. + equal variances, normality non-crucial is sample size at least 25. Assumptions: ea/pop of responses must follow normal model + two population variances are equal. If larger sd is no more than twice smaller sd = equal variance. Iqrs + overall ranges b/w two groups is super different; not pooled. Levene"s test for assessing if population variances are equal. If p-value is larger than = 0. 10, fail to reject ho and assume equal variances. If 0 is in the interval, then there is no difference. With 95% confidence, we estimate the difference in population mean time watching tv (mil-silent) to be between -1. 36 min up to 12. 13 min.