<p>I think Ross is similar in selectivity to Hampshire and PROMYS. While USA/Canada MathCamp may be the most selective the differences between the camps are large enough that you should go to the camp that fits you best. Working mainly by yourself on number theory at Ross is very different from the myriad of activities both math related and not math related at USA/Canada MathCamp. I’m not sure that I’d agree with MathCamp being the most respected math camp for high school students. Ross costs $2200 for six weeks which just goes towards room and board. MathCamp costs $4000 for five weeks. The only reason I can think of for Ross being so much cheaper than MathCamp is that while Ross receives lots of outside grants, MathCamp receives considerably less. This suggest that at least among grant-awarding institutions Ross is more well regarded. Ross is also much older and has spawned many other math camps like PROMYS which suggests that Ross has a greater influence in mathematical circles. The reason Ross is less selective is probably not because it is less prestigious but because it is considered to be less fun. MathCamp allows you to bring computers, go off campus without a counselor, organizes lots of field trips and other activities . At Ross you do math, more math, and even more math with only occasional other activities [typically no more than 1 frisbee game and 1 other activity per week]. If you want to math pretty much all day long every day than Ross is the place for you. If you’re not interested in such an intense experience then check out the other camps.</p>