Item Slam
Patch 7.41f
Butterfly in patch 7.41f: WPA of the purchase on 10 heroes, by role and build slot, against the other items bought in the same slot. Best confirmed result: Drow Ranger core, 4th+ item (+4.22 pp).
WPA of the item against the other items bought in the same slot, in matches of every rank. Slots with fewer than 30 purchases are left out.
| Hero | Role | Slot | Purchases | WPA | 95% CI | Verdict |
|---|---|---|---|---|---|---|
 Phantom Lancer | Core | 1st item | 38 (0.3%) | +7.94 | +3.14 to +12.50 | Inconclusive |
 Sniper | Core | 4th+ item | 184 (3.2%) | +7.56 | +4.30 to +10.85 | Inconclusive |
| Sniper | Core | 3rd item | 36 (0.9%) | +6.99 | +3.39 to +10.03 | Inconclusive |
 Slark | Core | 4th+ item | 283 (1.0%) | +6.44 | +2.53 to +9.39 | Inconclusive |
| Slark | Core | 3rd item | 41 (0.3%) | +6.30 | +2.89 to +9.36 | Inconclusive |
 Drow Ranger | Core | 1st item | 1,771 (4.6%) | +4.49 | +2.67 to +6.76 | Inconclusive |
| Drow Ranger | Core | 4th+ item | 5,117 (11.1%) | +4.22 | +3.41 to +4.90 | ✓ Better |
| Drow Ranger | Core | 3rd item | 6,253 (23.1%) | +3.06 | +2.27 to +3.84 | ✓ Better |
| Drow Ranger | Core | 2nd item | 3,059 (9.0%) | +2.70 | +1.27 to +4.11 | ✓ Better |
| Phantom Lancer | Core | 4th+ item | 1,145 (6.3%) | +2.60 | +1.00 to +4.27 | Inconclusive |
| Phantom Lancer | Core | 2nd item | 103 (0.9%) | +2.38 | −1.06 to +6.04 | Inconclusive |
 Anti-Mage | Core | 4th+ item | 2,753 (15.0%) | +2.08 | +0.94 to +3.40 | Inconclusive |
 Luna | Core | 4th+ item | 4,829 (10.8%) | +2.06 | +0.90 to +3.13 | Inconclusive |
| Luna | Core | 2nd item | 302 (1.8%) | +1.94 | +0.10 to +4.57 | Inconclusive |
| Anti-Mage | Core | 2nd item | 62 (0.5%) | +1.90 | −1.82 to +5.92 | Inconclusive |
 Juggernaut | Core | 2nd item | 990 (6.9%) | +1.58 | −0.13 to +3.79 | Inconclusive |
| Luna | Core | 3rd item | 4,345 (27.9%) | +1.50 | +0.66 to +2.49 | Inconclusive |
 Dragon Knight | Core | 4th+ item | 44 (0.1%) | +1.26 | −2.56 to +4.73 | Inconclusive |
| Juggernaut | Core | 3rd item | 5,596 (44.6%) | +0.95 | +0.34 to +1.67 | Inconclusive |
 Sven | Core | 4th+ item | 317 (0.8%) | +0.81 | −3.34 to +3.63 | Inconclusive |
 Lifestealer | Core | 4th+ item | 169 (0.8%) | +0.24 | −3.74 to +4.29 | Inconclusive |
| Juggernaut | Core | 4th+ item | 2,075 (7.9%) | −0.15 | −1.87 to +1.22 | Inconclusive |
| Phantom Lancer | Core | 3rd item | 244 (2.5%) | −0.37 | −4.16 to +2.66 | Inconclusive |
| Anti-Mage | Core | 3rd item | 4,174 (36.5%) | −0.42 | −1.47 to +0.46 | Inconclusive |
Win probability added: how much choosing an item changed the chance of winning, in percentage points, compared with what the hero usually buys in that same slot and situation. +1.0 means the choice won 1 percentage point more than the typical purchase. Unlike raw win rate, it accounts for the game state when the item was bought, so an item bought from ahead doesn't look good just because the game was already won.
1st, 2nd, 3rd and 4th+ count completed items. Components that become another item in most matches (Perseverance, Dragon Lance, Kaya) do not take a slot: the item they build into does. Boots get a card of their own.
The ✓ Better or ✕ Worse badge only appears when the effect passes the false discovery control (10%) in both ways of measuring: at the start of the decision and at the moment of purchase. Without a badge, the sign of the WPA is a trend.
Ranked (All Pick) matches parsed by OpenDota in the current patch. One model estimates the chance of winning from the game state; another, the effect of each item at the time of the decision. It is association, not causation: the model sees the game, not who is playing.