Bitplayer,

I’ve reviewed the study more closely and will try to answer your questions. It was conducted by geneticists Stephen Paul Harrison and Juan Luis Turrion-Gomez, and published in Mitochondrion- a peer-reviewed journal. They recognized several different haplotypes (gene arrangements) on mDNA, 5 of which correlate strongly with different racing abilities at 5 different distance ranges. The statistical methodology used was regression analysis and is presented in table and graphic form in the paper. Regression is a very effective way to show how different levels of one variable (genetic type) affect the values of another variable (racing performance).
Hope that answers your questions.

Bob