Hypothesis Testing in Introductory Biostatistics: Practice Problems, Study notes of Biostatistics

Download Hypothesis Testing in Introductory Biostatistics: Practice Problems and more Study notes Biostatistics in PDF only on Docsity! PubHlth 540 Introductory Biostatistics Page 1 of 2 Unit 7 – Hypothesis Testing Week #11 - Practice Problems This Assignment is optional (read: You all get full credit no matter what) 1. Before you begin: This exercise is a two sample(independent groups) t test of equality of means where the variances are unknown but assumed equal. See lecture notes for Unit 7(Hypothesis Testing) pp 40-43. See text pp 304-308. An independent testing agency was hired prior to the November 2004 election to study whether or not the work output is different for construction workers employed by the state and receiving prevailing wages versus construction workers in the private sector who are paid rates determined by the free market. A sample of 100 private sector workers reveals an average output of 74.3 parts per hour with a sample standard deviation of 16 parts per hour. A sample of 100 state workers reveals an average output of 69.7 parts per hour with a standard deviation of 18 parts per hour. You may assume equality of variances in your work. (a) Is there evidence of a difference in productivity at the 0.10 level of significance? (b) Is there evidence of a difference in productivity at the 0.05 level of significance? (c) What is the achieved level of significance? 2. Before you begin: This exercise is a continuation of the setting in Exercise 1.. For the data in Exercise 1, what level of significance is achieved by the data if the sample means and sample standard deviations are unchanged but the within group sample sizes are (a) both equal to 10 (b) both equal to 200 (c) Comment on the role of sample size in the probability of a type I error. Z:\...\Wk11_practice.doc