![null hypothesis test calculator null hypothesis test calculator](https://i.stack.imgur.com/ZKpCx.png)
This allows us to remove the extraneous effects of pre-existing individual differences between subjects. The idea is to replace the difference between the means of two sets with the mean difference between the paired observations.
![null hypothesis test calculator null hypothesis test calculator](https://image.slidesharecdn.com/standarderrorz-test-151223054009/95/ztest-and-standard-error-21-638.jpg)
This means that two sets of measures are arranged in pairs, where each item in one set is somehow linked with a corresponding item in another set. So, the test deals with correlated samples. This approach is sometimes used in observational studies to reduce or eliminate the effects of confounding factors. The pair is similar in terms of other measured variables. The matching is carried out by identifying pairs of values consisting of one observation from each of the two samples. Note, however, that an increase of statistical power comes at a price: more tests are required, each subject having to be tested twice.Ī paired samples t-test based on a "matched-pairs sample" results from an unpaired sample that is subsequently used to form a paired sample by using additional variables that were measured along with the variable of interest. That way, the correct rejection of the null hypothesis (here: of no difference made by the treatment) can become much more likely, with statistical power increasing simply because the random between-patient variation has now been eliminated. By comparing the same patient's numbers before and after treatment, we are effectively using each patient as their own control. Paired samples t-tests typically consist of a sample of matched pairs of similar units or one group of units that has been tested twice (a "repeated measures" t-test).Ī typical example of the repeated measures t-test would be where subjects are tested before treatment, say for high blood pressure, and the same subjects are tested again after treatment with a blood-pressure-lowering medication. The t-test is also known as Student's t-test, after the pen name of William Sealy Gosset. The calculator below implements paired sample t-test (also known as a dependent samples t-test or a t-test for correlated samples).