Guide to Using Minitab 14 For Basic Statistical Applications To Accompany Business Statistics: A Decision Making Approach, 8th Ed. Chapter 11: Hypothesis Tests for One and Two Population Variances By Groebner, Shannon, Fry, & Smith Prentice-Hall Publishing Company Copyright, 2011

Chapter 11 Minitab Examples ä ATM Transaction Times ATM Transaction Times ä Bank ATM Machines

Testing-Two Variances - Bank ATM Machines Issue: System programmers believe that the original ATM computer program will result in a higher standard deviation in transaction times than the new program Objective: Use Minitab to help test a hypothesis about the standard deviation of two groups. Data file is ATM.MTW

Testing-Two Variances - Bank ATM Machines Open File ATM.MTW

Select Stat, then Basic Statistics, then 2 Variances Testing-Two Variances - Bank ATM Machines

Select samples in different columns, specify location of data, click on options Testing-Two Variances - Bank ATM Machines

Enter (1 – alpha)100 in Confidence level box, click OK Testing-Two Variances - Bank ATM Machines

Minitab Results – F test statistic = Since p-value = is less than.01, reject the null hypothesis and conclude the variances are not equal. Testing-Two Variances - Bank ATM Machines

These are the results from the Textbook’s handling of the case.