Hello!

I would like to use the TTEST function to see whether two of our processes are the same. Here is what I mean:

We are sampling a chunk of mixed metal. We are sampling with a "shot" technique when it's a hot liquid, and another sample by drilling it after it cools.

Our lab will examine both samples at least 2x each (maybe 3 or 4) to determine what the sample is made up of (% of gold, silver, etc, contained in the sample).

So, I may have data that looks like this:

Shot sample, Gold: 10.28%, 10.27%
Drill sample, Gold: 10.21%, 10.25%

I want to compare the 2 percentages from the drill sample to the 2 percentages from the shot sample using a T-test to see if there's a difference in accuracy between the two processes.

My question is, when I do the formula, I am thinking it should be (=TTEST(A1:A2 (shot sample #s), B1:B2 (drill sample #s),2,1). I am pretty sure the "1" is correct, b/c this means I am using a paired sample. But I am not sure if I am using a 1 or 2-tailed test (as denoted by the "2" in the formula.

Can someone tell me if a t-test is appropriate for this situation, and if so, is my formula correct?