If the test was significant, the error bar will not overlap $0$. Tested in Flow Cytometry (Flow) applications. That is the actually the relevant plot for a pairwise $t$-test. Invitrogen Anti-CD45 Monoclonal (30-F11), eBioscience, Catalog 67-0451-82. If you like, you can even make a bar plot with a single forlorn-looking bar representing the mean difference with it's corresponding error bar. The pairwise (one-sample) $t$-test is the mean divided by the SE. Then you calculate the mean and standard error of those. Then you have only one variable: difference scores. That is, first subtract the pre-treatment value from the post-treatment value for each patient. To understand what a paired $t$-test is doing, you need to think of it as a one-sample $t$-test on the differences. It is fine to calculate and present pre- and post-treatment means and error bars, but it can lead to just this confusion. They are not the same thing, so they don't have to be consistent with each other. The reason is that your error bars are calculated on the between subjects data, but the test is of the within subjects data. Yes, it's quite possible for the $\pm 1$ SE error bars to overlap, but still have a significant pairwise $t$-test. My question is: in a paired data set, is it possible for there to be statistical significance between the control ($x$) and drug treatment ($y$) despite having overlapping standard errors? My $t$-test was done using GraphPad prism so I'm confident there are no errors in the $t$-test. However, I have conducted two-tailed paired $t$-tests on my data set (comparing the means of all values in $x$ versus the means of all values in $y$) and my results yield statistical significance with a $p$-value $< 0.05$ (despite there being overlapping standard error margins with data in $x$ and $y$). By standard error margin, I am referring to ($SE_\bar x = SD/\sqrt N$). I have seen in various texts stating that when standard error margins overlap, the data cannot significant. Each $x$ is the control for the corresponding $y$.
HOW TO ADD ERROR BARS IN GRAPHPAD PRISM PLUS
If you choose to format the table so the subcolumns are labeled mean, upper limit, and lower limit, you are welcome to enter into those subcolumns the median plus the 25th and 75th percentiles, or whatever values you want.
![how to add error bars in graphpad prism how to add error bars in graphpad prism](https://www.graphpad.com/guides/prism/7/statistics/images/hmfile_hash_8f589637.gif)
Or rather Prism will only analyze/fit the means and ignore the error values. $N=10$ for both $x$ and $y$ columns as they are paired data. If you choose to format the data table with subcolumns for Mean and SD or SEM or CV without sample size, or for mean with +- error values or upper and lower limits, no analyses will be possible.
![how to add error bars in graphpad prism how to add error bars in graphpad prism](https://cdn.graphpad.com/faq/1746/images/1746e.gif)
Particularly use the shaded error bars for plots with several data points. I have a paired data set which I have placed into $x$ and $y$ columns where $x$ are the control values and $y$ are the values following drug treatment. Is GraphPad Prism the right Statistical Analysis solution for your business.