Homework # 13 Problem # 15 on Page 469 #15 HYPOTHESES TEST STAT (1) F = s1^2/s2^2 Required Condition: Populations are approx Normal. (2) If Ho is true (var's equal), this ratio has a known "F" distribution with 2 df: df1=n1-1 = 20 df2=n2-1 = 25 SIG LEVEL Alpha = .05 REJECT RULE Reject Ho if F: < 0.4174 > 2.3005 CALCULATIONS N1 = 21 N2= 26 S21 = 8.2 S22 = 4 F = 2.05 p-value = 0.090 CONCLUSION DO NOT REJECT HO ANSWER According to the sample results from the two samples there is insufficent evidence to conclude the population variances are different given the significance level of 5% Even though there is a decent difference between the two variances, there is not enough of a difference given the two sample sizes to definitively be able to say they are different. Example From Class Notes 2-2: Issue: Variability/consistency in service times for two bank tellers. F-Test Suppose they had different training; we think teller 1's training might be better. Bus Question:
This is the end of the preview.
access the rest of the document.