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

Here is the output for the newer approach (Analyze>Non- parametric Test> Independent Samples…). It is easier to interpret BUT it uses the median test in line 1 and we have determined that the two groups do not have the same shape; therefore, use line 2 information. The confidence interval shown here at 95% is CI[80, 510]. It supports rejecting the null hypothesis because the confidence interval does not cross zero.

Table 119: New approach to analyze non-parametric test

EFFECT SIZE

The effect size tells us that the significance is not due to chance. Essentially, it indicates how strong of an observed effect and is quite helpful in additional studies. SPSS Version 27 does not calculate effect size for the Mann Whitney U test.

Everything you want to know about effect size!

Lenhard, W. & Lenhard, A. (2016). Calculation of Effect Sizes . Retrieved from: https://www.psychometrica.de/effect_size.html. Dettelbach (Germany): Psychometrica. DOI: 10.13140/RG.2.2.17823.92329

Ellis, P.D. (2009), "Thresholds for interpreting effect sizes," Polyu.edu.hk accessed on July 11, 2021.

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