# Can I still apply statistics to this problem?

I've an ongoing experiment. We're trying to determine if it's possible to detect if a bunny is infected with a disease through an electronic device over a period of time of 1 month. Since we couldn't get a higher volume of the virus we have to work with 3 control subjects and 3 infected subjects.

The problem is that we didn't realize that the subjects involved had two different blood types( A & B). So now we have Group A (2 control & 1 infected) and Group B (1 control & 2 infected).

The difference between blood types changes the magnitude obtained from the instrument.

My questions are, what type of analysis should I use (Specially for small samples/Data-sets)? Am I still able to divide them into control and infected groups? Is this problem reliable (in terms of statistics)? Is a test of standard deviations the best way to approach this?

• Yes you can apply probability and statistical analysis, but you'll have to make some assumptions that variables follow a certain distribution etc.... (eg. error term is normally distributed or something like that). Various statistical arguments that are based upon asymptotic results, arguments that require large samples (eg. that the sample mean converges to a normal random variable as $n \rightarrow \infty$) will almost certainly be inapplicable. – Matthew Gunn Sep 27 '16 at 21:43