I apologize in advance for the redundancy of my post (I've seen many other posts asking almost the same thing), but I am not familiar with statistical terminology which makes efficiently searching past posts difficult. Also, the nature of my data is slightly different than other examples and I'm unsure whether or not that makes the answers applicable to my scenario.
I have a dataset of genetic expression values for several genes, across many different human tissues. This is what it looks like:
gene tissue1 tissue2
1 gene_A 170.20 466.25
2 gene_B 6.50 9.05
3 gene_C 16.40 17.75
4 gene_D 13.90 30.50
Each value in the tissue columns is actually an average of several samples but I do not have data for those individual samples.
I want to determine which genes have the most statistically significant difference in expression between tissue1 and tissue2. Which statistical test is most appropriate here? What cautions should I keep in mind with that test?