I am measuring the energy consumption and runtime of computer programs and would like to select a subset of the programs that have stable energy / runtimes. Each program is ran 10 times and I measure the energy consumption and runtime of each run. Runtime is measured in seconds and energy consumption in Joules.
I plan to apply a series of optimisations to the chosen subset and measure the change in energy consumption and runtime. I want to ensure that any measured change in energy or runtime is due to the applied optimisations and not just due to natural variation so I want to have a principled way of selecting programs with stable runtimes and energy measurements across the multiple runs.
I would like to know if there are any metrics that would allow me to say something on the lines of "select programs that have energy and run time variation of less than $x$%"?