From: Consumer expectations, drug effects, price and purity of heroin and cocaine purchased at drug consumption rooms
Estimated potency (%)
Measured potency (%)
Bias between measured and estimated potency (%)
Mean
Median
Range
Heroin (n = 113)
32.0
25.0
0–80
16.6
16.5
1.5–56.3
+ 83.4
Cocaine (n = 74)
34.8
26.3
0–90
50.5
50.1
8.0–91.6
− 39.9