In other words, the difference between the two means is statistically significant. This means that we can reject the null hypothesis with a very low risk of being wrong. The p-value carries a similar information: p < 0.0001, which is lower than the significance level alpha (0.05). The 95% confidence interval on the difference between the two means (116.792) does not include the null hypothesized difference we chose (zero), which indicates that the mean difference between the two means is unlikely to be zero.
They are followed by the results of the paired t-test: The first results displayed are the statistics for the samples. Interpreting the results of a Student's paired t-test This reflects the null hypothesis we are willing to test: mean(sample 1) minus mean(sample 2) equal 0.Īfter you have clicked on the OK button, the results are displayed on a new Excel sheet. In the Options tab, we enter 0 in the hypothesized difference field. You can then select the data on the Excel sheet. Once you've clicked the button, the dialog box appears. Once XLSTAT-Pro is activated, select the XLSTAT / Parametric tests / Two-sample t-test and z-test command, or click on the corresponding button of the Parametric tests menu (see below). Setting up a Student's paired t-test on two paired samples
The goal of this tutorial is to compare the two periods with respect to the depression score.
The variable to be compared is a depression score. Patients have been followed at two different times (0: pre-test and 6: 6 months follow-up). The data correspond to an experiment in which depression is studied. If we had 30 plants for the morning measurements and 30 different plants for the afternoon measurements, the t-test for independent samples would be more appropriate. We say paired because every plant is measured twice, so data is organized by pairs. Student's paired t-test can be used to detect a change in photosynthesis between the two dates. For example: the photosynthetic rate of 30 plants is followed at two moments during the day: morning and afternoon. Student's paired t-test allows to compare the means of two series of measurements performed on the same statistical units. This tutorial will help you compare two observed means ( this guide).
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