I am having trouble understanding possessions in basketball as it seems like there are 3 equations. One that is (FGA+0.44*FTA+TO) and another that accounts for Offensive Rebounds found here. Lastly, the main one created by Dean Oliver found here. Are the first two estimates of possession, as in a much simply way to calculate possession?

My question stems from looking at some formulas like TOV% and Points per Possession. Seems like TOV uses the equation found above and PpP uses Oliver's equation. Why does this difference exist? Also are players TOV%/PpP different than a team's TOV%/PpP? I feel like the calculation should be the same, but using the teams numbers instead of a players.

What is Possession acording to SportingCharts:

A statistic in basketball defined as the time a team gains offensive possession of the ball until it scores, loses the ball, or commits a violation or foul. A possession in basketball is an important statistic because it allows teams to compute statistics on a per possession basis. The statistic can be applied to an individual player or the entire team.

Now we know what possession is, we can go further: how to calculate possession in Basketball?

The more realistic possession estimator is poss = FGA + 0.475 x FTA - ORB + TO

FGA - the number of field goal attempts

FTA - the number of free throw attempts

ORB - the number of offensive rebounds

TO - the number of turnovers. Possessions end on turnovers and on shots that the offense doesn't rebound.

0.475 - The consensus value for college basketball seems to be 0.475. In the NBA, 0.44 is typically used.