Sign Test

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When to use it:

- When looking for a test of difference between two conditions

-When the data is numerical

-With repeated measures or matched pairs design

How to:

List the participant scores for both conditions and work out the difference in these scores.

Next to their score indicate whether their score has decreased with a - or increased with a + , or ignore the data if there has been no change.

Decide whether a directional or non-directional hypothesis is being used.

Decide which 'p value' is being used.

Identify the number of participants who showed a difference in scores.

Find the calculated value known as 'S' by adding the total number of pluses and minuses in the table and selecting the smaller of the two. (i.e there's two pluses and four minuses, so you choose 2).

Then find the critical value using the critical value table.

For the results to be statistically significant the calculated value (S) must be equal to or less than the critical value.

If the critical value is more or equal to S you must accept the experimental hypothesis and reject the null hypothesis.

If the critical value is less than S you must reject the experimental hypothesis and accept the null hypothesis.

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Example