2022 Introduction to Statistics in Research Mitchell 2nd ed

I N T R O T O R E S E A R C H : D A T A V I S U A L I Z A T I O N & C O M M O N S T A T T E S T S

#2 – Interpretation Choice -Look at probability.

The second way to determine if we should reject the null hypothesis is to look at the Exact Sig (2-tailed) value .011. Again, we would reject the null hypothesis since this value is less than .05.

Compare this value to the critical value from a table using 11 for group 1 and group 2 and an alpha level of .05. Make sure to understand which critical value table to use. If the critical value (table) is greater than the calculated t-value, reject the null hypothesis.

#3 – Confidence Interval

In a Mann Whitney U test, we use the Hodges-Lehmann estimate (2 samples) to determine the confidence interval. Although you can use the legacy dialog to get you U test statistic, you need to run the newer approach to find the confidence interval as shown in this illustration in the settings tab. This is shown in detail in the video that follows this section.

Table 118: Illustration for Step 3 - Estimate Confidence Interval across groups

Link to Mann-Whitney U Critical Values tables: http://ocw.umb.edu/psychology/psych-270/other- materials/RelativeResourceManager.pdf

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