A variety of outputs which predict the effects of different grade hills on pace and race performance. Obviously, human beings are not as predictable as, say, solar eclipses, so no model will be accurate for everyone all of the time. Not only does one's physical state vary widely from day to day, but the crucial mental component may be quite fickle as well. The type of runner that this program really models well is the diligent, mentally strong type who trains intelli- gently and can perform up to potential at will. There actually are a lot of runners like this, even in high school.
Self trained runners often have the self discipline to perform consistently as well.
Course conditions and weather can have major and obvious effects as well. The program may have trouble predicting cross country times, as it really requires the consistency of a track or flat course for best results. Heat, while a rather minor factor in races lasting only a few minutes, really takes a toll in longer events. Basically the program can only be as accurate as the runner and conditions are consistent. As for training data, the 'miles per week' is perhaps best thought of as an average over the last two months or so.