In the ophthalmoinnovations blog I read a post where they wanted to know if the aspheric laser treatments where really aspheric so they put it to the test. The result was yes but to claim this they only give the mean Q values for the planoscan - not aspheric treament - group and the aspheric treatment group. I asked J.R.Villada, the author, if I could have a look at the data to see it better with graphs and he kindly agreed. So I had two set of Q values, one for the planoscan and one for the aspheric treatments with Q values preop and postop. Now first things first, let's look at the distributions:

 

 asf1

 

There are 97 eyes for the aspheric treatment and 75 eyes for the planoscan, the distributions are reasonably normal, although the postops after the aspheric treatment distribution is a bit right skewed. Let's make some boxplots to see both groups:

 

asf2

 

Well it seems indeed that the aspheric treatment is doing its job making the corneas less oblates. A t-test shows that the preop patients group means are not significantly different, means -0.18 and -0.17 and p value of 0.45, but after the treatment the means are significant, 0.10 and 0.31 and with a p value of 2.3e-7 or 0.00000023, virtually zero.