How Do I Run a Two Sample Comparison Test in Excel Using SigmaXL?We will now do a full comparison test of Customer Satisfaction for Customer Type 1 and 2. This test checks each sample for normality, equal variance (F-test and Levene’s), 2 sample t-test (assuming equal and unequal variance), and Mann Whitney test for equal Medians. Depending on the normality, variance, and sample size results, the appropriate p-values are highlighted in yellow.
Two Sample Comparison Test
- Open Customer Data.xls, click on Sheet 1 Tab.
- Click SigmaXL > Statistical Tools > 2 Sample Comparison Tests. Click Next. Check Stacked Column Format. Select Overall Satisfaction, click Numeric Data Variable (Y) >>, select Customer Type, click Group Category (X) >>.
- Click OK. Select Customer Type 1 and 2.
- Click OK.
Customer Type 2 has non-normal data. This makes Levene’s test the appropriate test for unequal variance. Levene’s test indicates that Customer type 2 has a significantly lower variance, or standard deviation. The lower standard deviation translates to a consistent level of satisfaction.
Since Levene’s test indicates unequal variance, the appropriate t-test assumes unequal variance. The t-test indicates that Customer Type 2 has a significantly higher mean satisfaction.
Clearly the next step would be to determine a root cause or best practices to reduce the variability in overall satisfaction and increase the mean for all customer types.
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