Not sure which (nonparametric) test to use? You’ll quickly find the answer in Simple Overview Statistical Comparison Tests.
What is a Kolmogorov-Smirnov normality test? SPSS Kolmogorov-Smirnov test from NPAR TESTS SPSS Kolmogorov-Smirnov test from EXAMINE VARIABLES Reporting a Kolmogorov-Smirnov Test Wrong Results in SPSS? What is a Kolmogorov-Smirnov normality test? The Kolmogorov-Smirnov test examines if scores are likely to follow some distribution in some population.For avoiding confusion, there’s 2 Kolmogorov-Smirnov tests: there’s the one […]
For testing if 3 or more variables have identical population means, our first option is a repeated measures ANOVA. This requires our data to meet some assumptions -like normally distributed variables. If such assumptions aren’t met, then our second option is the Friedman test: a nonparametric alternative for a repeated-measures ANOVA. Strictly, the Friedman test can […]
SPSS Cochran Q test is a procedure for testing if the proportions of 3 or more dichotomous variables are equal in some population. These outcome variables have been measured on the same people or other statistical units. SPSS Cochran Q Test Example The principal of some university wants to know whether three examns are equally difficult. Fifteen […]
The sign test for two medians evaluates if 2 variables measured on 1 group of cases are likely to have equal population medians.* It can be used on either metric variables or ordinal variables. For comparing means rather than medians, the paired samples t-test and Wilcoxon signed-ranks test are better options. Adratings Data We’ll use adratings.sav throughout this tutorial. It holds data on 18 respondents […]
For comparing two metric variables measured on one group of cases, our first choice is the paired-samples t-test. This requires the difference scores to be normally distributed in our population. If this assumption isn’t met, we can use Wilcoxon S-R test instead. It can also be used on ordinal variables -although ties may be a real issue for Likert items. […]
SPSS McNemar test is a procedure for testing if the proportions of two dichotomous variables are equal in some population. The two variables have been measured on the same cases. SPSS McNemar Test Example A marketeer wants to know whether two products are equally appealing. He asks 20 participants to try out both products and […]
The Kruskal-Wallis test is an alternative for a one-way ANOVA if the assumptions of the latter are violated. We’ll show in a minute why that’s the case with creatine.sav, the data we’ll use in this tutorial. But let’s first take a quick look at what’s in the data anyway. Quick Data Description Our data contain the result of a small […]
The median test for independent medians tests if two or more populations have equal medians on some variable. That is, we’re comparing 2(+) groups of cases on 1 variable at a time. Rating Car Commercials We’ll demonstrate the median test on adratings.sav. This file holds data on 18 respondents who rated 3 different car commercials on […]
The Mann-Whitney test is an alternative for the independent samples t test when the assumptions required by the latter aren’t met by the data. The most common scenario is testing a non normally distributed outcome variable in a small sample (say, n < 25).* The Mann-Whitney test is also known as the Wilcoxon test for independent samples -which shouldn’t be confused […]
If you’d like to know if 2 groups of people score similarly on 1 dichotomous variable, you’ll compare 2 independent proportions. There’s two basic ways to do so: the chi-square independence test and; the z-test for 2 independent proportions. These tests yield identical significance levels but the z-test approach allows you to compute a confidence interval for the difference between […]
A sign test for one median is often used instead of a one sample t-test when the latter’s assumptions aren’t met by the data. The most common scenario is analyzing a variable which doesn’t seem normally distributed with few (say n < 30) observations. * This tutorial shows how to run and interpret a sign test in SPSS. We’ll […]
The binomial test is the most simple statistical test there is. Understanding how it works shouldn’t be too hard and will help you understand other statistical tests more easily too. So what is it? A binomial test is a procedure for evaluating if some population proportion is x. For example, a marketeer has to make sure that 50% […]
There’s two basic tests for testing a single proportion: the binomial test and the z-test for a single proportion. For larger samples, these tests result in roughly similar significance levels. However, the binomial test only comes up with a 1-tailed p-value unless the hypothesized proportion = 0.5. Moreover, it can’t compute a confidence interval for your proportion. The […]
SPSS binomial test is used for testing whether a proportion from a single dichotomous variable is equal to a presumed population value. The figure illustrates the basic idea. SPSS Binomial Test Example A biologist claims that 75% of a population of spiders consist of female spiders. With a lot of effort he collects 15 spiders, 7 of […]
