Hopefully someone here can give me an answer to this question.

I have to run a statistical analysis on a data set I obtained recently.

This is my problem:

An individual was instructed to look at three possible computer screens and we measured how many times they fixated within a particular area.

Two screens had an area of 4 units.
The third screen had an area of 5 units.

The two screens having an area of 4 units obtained 15 fixations each while the screen of 5 units obtained 20 fixations.

Prior to running any statistical analysis to see if there is a significant difference between screen type and the number of fixations, I have to correct for the differences due to screen size (as a larger screen area would naturally result in more fixations).

Any help in how to do this correction would be appreciated (I provided arbitrary numbers as our data set is somewhat more complex, but if you could help me with the numbers provided, I should be able to easily adapt it to our data).

Thanks,
Shawn