Using data since 2021, home court advantage in the NBA is about 2.5 points. But are some home courts more advantageous than others? Here’s the home court advantage for all 30 teams in the NBA.
As usual, we aren’t just interested in the single number for home court advantage for each time. We also care about how certain we are about those numbers. There is only 41 home games each season, and scores vary wildly across games, so it might be hard to get a precise number for home court advantage.
Take Sacramento. Their home court advantage is -2 (home court disadvantage?), but it could really be anywhere from 0 to -4. Denver’s home court advantage can be anywhere from 2 to 6. But what we know for sure is Denver’s home court advantage is higher than Sacramento’s.
Golden State has the highest home court advantage. But we actually aren’t certain that they have the best home court advantage. Comparing them to San Antonio, for example, we see a lot of overlap.
Stan Model
You can stop reading. This section is only for people curious about the underlying probability model. Either because they want to understand the details or they want to expand on it themselves. Here's my Stan model.
This is a fairly straightforward model where home team advantage for each team is hierarchically modeled.
data {
int<lower=0> n_teams;
int<lower=0> n_games;
int home_team[n_games];
vector[n_games] score_differential;
}
parameters {
vector[n_teams] theta;
real<lower=0> sigma;
real theta_bar;
real<lower=0> sigma_bar;
}
model {
theta_bar ~ normal(0, 10);
sigma_bar ~ cauchy(0, 5);
theta ~ normal(theta_bar, sigma_bar);
sigma ~ cauchy(0, 5);
for(game in 1:n_games) {
score_differential[game] ~ normal(theta[home_team[game]], sigma);
}
}