According to new research from the University of Pennsylvania, the typical joint contains an average of .32 grams of marijuana, less than the .5 gram baseline used by the U.S. Office of National Drug Control Policy. The study is published in the August issue of Drug and Alcohol Dependence.
“It turns out to be a critical number in estimating how much marijuana is being consumed [nationwide], how much drug-trafficking organizations are putting on the market and how much states might expect in revenue post-legalization,” study co-author Greg Ridgeway, associate professor of criminology and statistics at Penn, said in a statement.
Ridgeway, along with Beau Kilmer of the RAND Corporation, used information from more than 10,600 cannabis transactions over 11 years from more than 40 communities. Through the Justice Department’s Arrestee Drug Abuse Monitoring program, researchers interviewed arrestees about drug abuse and market transactions, including whether joints or loose marijuana was purchased and how much was paid.
According to Ridgeway, some of the interviewees told researchers about purchases in grams or ounces, and others about purchases in joints — the interviewee disclosed how much they paid regardless of the form of cannabis purchased.
“If I paid $5 for a joint and you paid $5 for 0.5 grams, that gives me some information,” he said in the statement. “If they’re the same price, they must be roughly the same weight.”
Using a drug-pricing model “that’s been in use for about 30 years,” which factors in additional data – such as drug markets, inflation, where the sale occurred, and possible bulk discounts – the team was able to “untangle weight and price to estimate an average joint weight.”
“That all boils down to about 0.3 grams, which is much less than previously thought,” Ridgeway concluded.