March Madness

Going to be in Vegas for the first round of the NCAA Tournament (March 18-21). We go every year to bet on games. For the last 8 years, we pick games as a group and my father places the bets. We are never really sure if we have a two team or four team parlay until he shows us the wining/losing tickets. This year – I am going to place the bets. Is there any study on the return of parlay bets? For instance – the return is obviously better on a 3 team parlay than a 2 team. The odds at winning a two team parlay, however, are better. Is there some statistical analysis out there to support, one way or another, whether the return is greater by making multiple 2 and 3 team parlay bets or are the odds better (and return greater) by placing a couple of large 4 team parlays?
Thanks.