Ranges are generally constructed in one of three ways - Equity, Playability, and Expected Value.
Preflop Equity, or All-in Equity, is generally misunderstood. If you wanted to know the Equity of a specific 2 card hand you could use a poker simulator like PokerStove. It would simulate millions of hands in a range against the two cards. It assumes that it is an all-in condition, no bets or raises. The math is valid, but ignoring the other streets is not a good idea.
Preflop Playability is generally based on a consensus, not mathematics. Power-Equilab probably has the best. I believe theirs to be far better than Equity because it considers opponent actions on all streets. But the science behind it is elusive.
Preflop Expected Value is what works the best. The problem is that the calculation is impossibly complex and beyond the capability of most computers. EV can be calculated for specific conditions but not a full game. But, preflop EV can be estimated very closely by simulation a full game, with a full table, and with each player having a different strategy.
EV results for just a few hands:
If sorted by EV it's a good way to create a range of a specific percentage. The exact method is what I filed for a patent on. 62/732,519.
PeakHoldem can dramatically improve your win rate.
Every future release of PeakHoldem will increase the accuracy of opponent play.
Unique enough to be patent pending. 62/732,519.