What must you assume when you use a rate to make a prediction

For what kind of rate? Speed, growing, projectile?

For anything to do with force you have to assume an even amount of force is spread out evenly. But for things like growing rate you have all those variables so you can't assume a constant growing rate like acceleration.

I would assume that someone wants to do better than someone else so you have to rate them and see who has the most rates. Or who needs more rates.