I have absolutely no clue what you are looking for. If you are trying to use the principles of independent and dependent variable control to predict which popcorn pops the most kernels, then check out these sites.
This site just hit ctrl F and search for popcorn. Then read the script.
This link is a kid's science fair project but I think it gets the point across. Hit ctrl F and search for variable and you should get what this student listed as their independent/dependent variable.
Now, as for which brand really does pop the most kernals?
Read the results from this experiment. It shows that Act II Premeir Theatre popcorn pops the most.
This link is another question board with answers from different people.
Hope this helps.