Tekentest voor gematchte paren

Consider the data on hamsters' speed before and after administering a stimulant, which constitutes a matched pair. How does one test the claim that the stimulant impacts the hamster's speed?

Since the population distribution is unknown, the sign test—a nonparametric test—can be used.

The central concept of the sign test is that matched pairs with equal medians have approximately equal numbers of positive and negative signs.

First, convert the raw data into signs by subtracting the value of the second variable from the first variable. After excluding zeros, eight signs are obtained: three positive and five negative.

The null hypothesis posits that the median of the differences is zero, whereas the alternative hypothesis suggests otherwise.

Since n is less than 25, the test statistic x is the number of the less frequent sign. From the table, the critical value is zero at a significance level of 0.05.

Since the test statistic value is not less than or equal to the critical value, there is insufficient evidence to reject the claim that the median of the differences is zero.