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#Paired sample t test spss how to#

Please click here if you need a detailed tutorial on how to perform this in SPSS with sample data and how interpret and report it(we use APA/HAVARD styles)Īlso look at our quick guide on independent sample t-test and one sample t-test.įeel free to contact us any time for our services.

Move the variable pair(s) you’d like to test to the fields variable 1 and variable 2 in the box paired variables.

Quick guide on a Paired sample t-test in SPSS.įollow the following procedure to perform a paired sample t-test in spss.

The distribution of the differences in the dependent variable between the two related groups should be approximately normally distributed.

There should be no significant outliers in the differences between the two related groups(di).

“Related groups” indicates that the same subjects are present in both groups

I ndependent variable consists of two categorical, “ related groups ” or “ matched pairs “.

eg time taken for an athlete to complete a track, marks scored by a student.

D ependent variable is continuous ( interval / ratio ).

Where t α is the critical value for a two-sided test with n – 1 degrees of freedom.īefore we carry out this test, we need to be familiar with the following assumptions. A 100(1 – α)% confidence interval can be constructed as follows:

A one sample t-test tests the mean of a single group against a. A paired sample t-test compares means from the same group at different times one year apart, for example. An independent samples t-test compares the means for two groups. Under the null hypothesis, the test-statistic has a t-distribution with n – 1 degrees of freedom. The three main types of t-test are independent sample t-test, paired sample t-test, and one sample t-test. Where Edit dbar is the mean difference between the paired groups and sd is the standard deviation of the differences di and n the number of pairs. The null hypothesis here is that the mean difference is zero,ie, Ho:Qd = 0.The paired t-statistic is If the values of the variables of interest y for the members of the ith pair in groups 1 and 2 are denoted as y1i and y2i, then the differences Edit di = y1i – y2i are assumed to have a normal distribution.

Examples are the types of data that show “before and after” treatments.Ī real life example is a study to establish whether a drug reverses the state anemia in malaria patients where you are given data on the haemoglobin levels of ten patients before and ten days after treatment. A paired sample t-test is used to compare the means of two populations when samples from the populations are available, in which each individual in one sample is paired with an individual in the other sample.