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==Comparing a quantitative variable between two groups==
==Comparing a quantitative variable between two groups==
===t-test===
===t-test===
The t-test (also known as the 'Student's t-test') is the most commonly used test for the comparison of two normally distributed variables, and can also be used to assess whether a single normally distributed variable differs from a particular value. As for many hypothesis tests, it involves the calculation of a test statistic which is assumed to follow a particular distribution (in this case, the t distribution). When calculating the test statistic for the comparison of two distributions with approximately equal variances and equal numbers of individuals in each group, the difference in mean values between the two groups is divided by the standard error of the difference between these two means (which is calculated as the product of the pooled standard deviation and the square root of two divided by the number of individuals in each group.
===Mann-Whitney U test===
===Mann-Whitney U test===