The symptoms of a sty are. foreign body sensation in the eye (particularly with blinking), eye pressure, and; pain in the area of the bump, though often they are painless. There may also be blurred vision if thick sebum or pus from within the sty spreads over the eye's surface. If chronic meibomian gland dysfunction is present, dry eye symptoms are common.
Paired t-test. This tutorial will walk you through the use of the paired t-test. The paired t-test should be used when the data are in pairs. One of the most common uses of this test is a before- and after- (pre and post) analysis. For example, we might be interested in how much a certain group grows after fertilizer is added to randomly selected plots.
There are four assumptions that underpin the paired t-test. If any of these four assumptions are not met, you cannot analyse your data using a paired t-test because you will not get a valid result. Since assumptions #1 and #2 relate to your study design and choice of variables, they cannot be tested for using Stata.