A free throw attempt is one recorded foul shot, whether it is made or missed. In play-by-play data, every attempt has event_type equal to “free throw”; result distinguishes made from missed attempts. Defensive fouls often award an offensive player one, usually two, and sometimes three attempts. section 16.2
At the team-game level, FTA is the number of free throws attempted and FT is the number made. Keeping them separate lets an analysis compare opportunity—how often teams reach the line—with conversion rate—how often they make those shots. section 7.3 section 7.4.1
Home versus road attempts
During the 2018–19 regular season, home teams averaged 23.40 free throw attempts per game and road teams 22.75: a difference of about 0.65 attempts per game. Both groups made about 77% of their attempts, so the observed difference concerns volume rather than efficiency. section 7.4.1
fouls1819 %>% filter(dataset == "NBA 2018-2019 Regular Season") -> fouls1819reg sum(fouls1819reg$pfR) - sum(fouls1819reg$pfH) ## [1] 470 mean(fouls1819reg$pfR) - mean(fouls1819reg$pfH) ## [1] 0.3821138 mean(fouls1819reg$ftaR) - mean(fouls1819reg$ftaH) ## [1] -0.6504065 sum(fouls1819reg$ftR) / sum(fouls1819reg$ftaR) ## [1] 0.7655742 sum(fouls1819reg$ftH) / sum(fouls1819reg$ftaH) ## [1] 0.7670176
This R calculation compares home and road FTA means, then divides made free throws by attempts to compute each side’s conversion rate. section 7.4.1
Attempt counts can help test an officiating-bias question, but they do not establish its cause. In the larger 2018–19 sample, the home-road attempt difference was statistically significant; in the shorter post-COVID sample, the small difference was not significant. Across comparisons, effect sizes were negligible. section 7.4.1 section 7.5.2 section 7.6
