Yep.
People also like to talk about the "high" or "low" range of average. A 'range' with respect to an average (or a median, which I think makes more sense with body sizes -- the average isn't always where 50% are bigger and 50% are smaller) should be taken as 1 standard deviation away, since that's effectively where most of the sample falls.
Standard deviation is the average amount that something varies from the average. Whenever people here talk about what constitutes a "big" or "small" dick, the only good way to do this is to just look at the standard deviation. Being within one standard deviation is what you should consider the 'average' range, being above one but within two deviations is 'small' or 'big', and anywhere outside of 2 would be 'tiny' or 'huge'. Outside 3 is an extremely uncommon occurrence, and is considered medically abnormal.
So these numbers are from some higher deviating studies, but the highest deviation is 0.7", and the average most medical studies place for BPEL is 5.5" or a little below that.
-2 dev : 4.1"
-1 dev : 4.8"
0 : 5.5"
+1 dev : 6.2"
+2 dev : 6.9"
We seem to naturally understand deviation when it comes to human height : someone a few inches taller than someone else is noticeably much taller, even though as a percentage difference in height that's generally <4%. Our brains know what the variability is, so we naturally see these few inches of height difference as a major difference in size. We apply the same thinking to dicks, but since we don't really know the numbers someone an inch longer than someone else looks (and is) a lot longer, but we often believe that's 2-3 inches more.