If you wanted to graph something, you needed a ruler, a sharp pencil, and some Letraset for the labels, and that's without touching on having to use log scales and drawing curves by hand. There was no PubMed, and definitely no Papers, so searching the literature involved hours spent at a desk in the library poring over Index Medicus. Of course, back in those days, everything was harder. But in a perfect example of letting the silicon chip do the heavy lifting, programs were written that would calculate those for you. Back before the widespread use of computers in research, it was tough luck-you had better know how to calculate t tests or regressions. And just about anyone who has taken a stats course at university can tell you that calculating statistical significance is both hard and boring.
Use the drawing tool to add the line below the asterisks, then right-click and set the arrow heads to "half tick down'. This creates a live link, so if you edit or replace the data, the number of asterisks may change (or change to 'ns'). To add the asterisks representing significance level copy from the results table and paste onto the graph.Avoid using a bar graph, since it can only show the mean and SD of each group, and not the individual changes.This example plots each subject as an arrow to clearly show the direction from 'before' to 'after', but you may prefer to plot just lines, or lines with symbols. A before-after graph shows all the data.Learn more about interpreting the results of a paired t test.īefore accepting the results, review the analysis checklist. So the most important results are the 95% confidence interval for that difference and the P value. The t test investigates the likelihood that the difference between the means of the two groups could have been caused by chance. Leave this set to 95%, unless you have a good reason to change it. This choice only affects the sign of the difference and the confidence interval of the difference, without affecting the P value. Choose the direction of the differences.On the first (Experimental Design) tab of t test dialog, make these choices:Ĥ. Choose t tests from the list of column analyses.ģ. From the data table, click on the toolbar.Ģ. Optionally, enter row labels to identify the source of the data for each row (i.e.
If you leave any missing values, that row will simply be ignored. If you are not ready to enter your own data, choose sample data and choose: t test - Paired.Įnter the data for each group into a separate column, with matched values on the same row. From the Welcome (or New Table and graph) dialog, choose the Column tab.
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