wnba_rapm: *Fit a Ridge-Regression RAPM Model from WNBA Possession Data*

In wehoop: Access Women's Basketball Play by Play Data

Fit a Ridge-Regression RAPM Model from WNBA Possession Data

Description

Fit a Ridge-Regression RAPM Model from WNBA Possession Data

Fit a Ridge-Regression RAPM Model from WNBA Possession Data

Usage

wnba_rapm(possessions, ...)

Arguments

possessions	A possession-level stint matrix as produced by wnba_possession_lineups(), with columns off_player_1 through off_player_5, def_player_1 through def_player_5 (integer WNBA Stats person IDs), and points (numeric, points scored on that possession).
...	Reserved for future keyword arguments (currently ignored).

Value

Returns a data.frame with one row per player:

col_name	types	description
player_id	integer	WNBA Stats person ID. Rows are sorted ascending by player_id.
o_rapm	numeric	Offensive RAPM (per-100-possession points added on offense). Positive = better offensive player.
d_rapm	numeric	Defensive RAPM (per-100-possession points saved on defense). Positive = better defensive player (sign is flipped so good defense is positive).
rapm	numeric	Total RAPM = o_rapm + d_rapm. Positive = net positive impact.
off_poss	integer	Number of possessions the player appeared on offense.
def_poss	integer	Number of possessions the player appeared on defense.

Returns a 0-row frame with the same schema when input is empty or all possessions have NA lineup cells (never-raise).

Note: RAPM is expressed in per-100-possession units. A full season of possessions (~3,000–5,000) is needed for statistically meaningful estimates. Results from a single game (~120–200 possessions) are highly unstable and are provided here for pipeline illustration only.

Results are deterministic: the cross-validation uses fixed, construction-based folds (not random), so repeated calls on the same possessions return identical output with no need to set a seed.

Author(s)

Saiem Gilani

See Also

Other WNBA Lineup Functions: wnba_gamerotation(), wnba_leaguedashlineups(), wnba_leaguelineupviz(), wnba_possession_lineups(), wnba_shot_zones(), wnba_shotchartlineupdetail(), wnba_teamdashlineups()

wehoop documentation built on Aug. 25, 2026, 1:06 a.m.