Statistical Tests
In this section we have a wide range of statistical tests that can be used to test your data. There is responsibility in collecting and analysing data and we need to be able to say whether our findings are statistically significant or not.
While descriptive statistics are used to summarise data characteristics, inferential statistics go beyond this and are used to make predictions, to test hypotheses or to find correlations/relationships based on data.
It can be very hard to know which statistical tests are the most relevant for your research question and your data. We provide a decision tree below.
Overview of statistical tests (with links) provides an overview of the different statistical tests, including our suggested online calculator for each test.
ANOVA
A one-way ANOVA (“analysis of variance”) compares the means of three or more independent groups to determine whether there is a statistically significant difference between the corresponding population...
Chi-square Tests
Chi-square tests look at the pattern of your data points and tell you if certain combinations of the categories occur more frequently than would be expected by chance.This section explains the Chi-square...
Kruskal-Wallis Test
A Kruskal-Wallis test is used to determine whether there is a statistically significant difference between the medians of three or more independent groups. This test does not assume normality in the data...
Mann Whitney U-Test
A Mann-Whitney U-Test is used to compare the differences between two independent samples when the sample distributions are not normally distributed and the sample sizes are small (n < 30).
Pearson Correlation Coefficient
The Pearson correlation coefficient (also known as the “product-moment correlation coefficient”) is a measure of the linear association between two variables X and Y. It has a value between -1 and...
Regression
Regression is the statistical approach to find the relationship between variables. It allows you to estimate the value of a dependent variable (Y) from a given independent variable (X).
Shapiro-Wilk Test
Some statistical tests ask you to assume that your data follows a normal distribution. The Shapiro-Wilk Test compares your data to data from a normal distribution with the same mean and standard deviation...
Spearman Rank Correlation
Spearman’s rank correlation is a measure of the association between two variables. It has a value between -1 and 1. This calculation does not require your data to be normally distributed.
t-Test
The t-Test tells you how significant the differences between group means are. It lets you know if those differences in means could have happened by chance. The t-Test is used when data sets follow a normal...
Wilcoxon Rank Test
The Wilcoxon Rank Test is used to test whether there is a significant difference between two repeated (paired) sample medians when your data cannot be assumed to be normally distributed.