Why election results are often not an accurate measure of the opinion of a majority of the voters?

Why election results are often not an accurate measure of the opinion of a majority of the voters? also what does the Electoral college system have to do with it?

acyberwin:
Because you are thinking in terms of one great national election... which simple isn't the case. There are 50 state elections, each governed by the states themselves.

I suggest reading article 2 of the Constitution.
The fact is, we were never intended to vote for president at all. The states were to choose electors and THEY would vote for the president with the second place winner becoming vice president.

Now each state commits its electors based on popular vote in that state... But the fact remains, there is no national election for president.