I have looked around and haven't been able to find an answer to this question. Seems like an easy question, so maybe it's just a matter of looking in the wrong place.
I have a data set representing performance of assets across a large region. The assets are broken up into subregions as well. I can calculate mean and standard deviation for the region, and for the subregions.
How can I test if a subregion's performance is significantly worse or better than the overall region?
Here's some of my data:
Overall: mean: 40% standard deviation: 15.3% sample size: 74 Sub-region A: mean: 43% standard deviation: 8.7% sample size: 10
I have 9 subregions. I think the answer might be some kind of T-test, but I'm not sure exactly which one is appropriate. Is sub region A significantly better than the overall average? Note: Sub region A's data is included in the overall statistics.