What the 6th Man Does

There is a home court advantage.  This is true across sport and level.  Calpreps says the home teams gains about 3 points of margin in high school basketball, all else being equal.

This Freakonomics post summarizes research suggesting that most of the advantage is due to officiating, not travel or playing in front of supportive fans.

Adding to their evidence, I'd like to draw your attention to a super cool website that keeps stats on officials.  This is a list of NCAA basketball officials, by the number of games they have called this year.  The column labeled "HM" is the "Home Margin" of fouls.  A negative number means that the official has been on crews that called fewer fouls on home teams than visiting teams.  A positive number means the official has been on crews calling fewer fouls on the visiting team.  If you go down the list you don't find a visitor friendly official until #74 - Winston Stith.  He is the only one on the list.  To further emphasize how rare this is, consider that even visitor loving Mr. Stith, in his 16th year of officiating, has had a negative Home Margin for the first fifteen.