What factors of the integer dataset being sorted can I change, in order to compare two sorting algorithms?

I am comparing two comparison and binary data structure based sorting algorithms, the Tree Sort, and the Heap Sort. I am measuring the time taken for both algorithms to sort an increasing size of an integer dataset. However, I am wondering if there are any other variables which I can modify, for example standard deviation, in the integer dataset itself that would be of any benefit to my comparison.