Concurrent validity of the marijuana purchase task: a meta‐analysis of trait‐level cannabis demand and cannabis involvement

Abstract

Background and aims The Marijuana Purchase Task (MPT) is increasingly used to measure cannabis reinforcing value and has potential use for cannabis etiological and regulatory research. This meta‐analysis sought to evaluate for the first time the MPT's concurrent validity in relation to cannabis involvement. Methods Electronic databases and pre‐print repositories were searched for MPT studies that examined the cross‐sectional relationship between frequency and quantity of cannabis use, problems, dependence, and five MPT indicators: intensity (i.e. unrestricted consumption), Omax (i.e. maximum consumption), Pmax (i.e. price at which demand becomes elastic), breakpoint (i.e. first price at which consumption ceases), and elasticity (i.e. sensitivity to rising costs). Random effects meta‐analyses of cross‐sectional effect sizes were conducted, with Q tests for examining differences by cannabis variables, meta‐regression to test quantitative moderators, and publication bias assessment. Moderators included sex, number of MPT prices, variable transformations, and year of publication. Populations included community and clinical samples. Results The searches yielded 14 studies (n = 4077, median % females: 44.8%: weighted average age = 29.08 [SD = 6.82]), published between 2015 and 2022. Intensity, Omax, and elasticity showed the most robust concurrent validity (|r's| = 0.147–325, ps < 0.014) with the largest significant effect sizes for quantity (|r| intensity = 0.325) and cannabis dependence (|r| Omax = 0.320, |r| intensity = 0.305, |r| elasticity = 0.303). Higher proportion of males was associated with increased estimates for elasticity‐quantity and Pmax‐problems. Higher number of MPT prices significantly altered magnitude of effects sizes for Pmax and problems, suggesting biased estimations if excessively low prices are considered. Methodological quality was generally good, and minimal evidence of publication bias was observed. Conclusions The marijuana purchase task presents adequate concurrent validity to measure cannabis demand, most robustly for intensity, Omax, and elasticity. Moderating effects by sex suggest potentially meaningful sex differences in the reinforcing value of cannabis.

Reliability and validity of behavioral‐economic measures: A review and synthesis of discounting and demand

“…The evidence also suggests that intensity and O max appear more reliable than break point, P max , and α. This is notable given recent meta‐analyses reporting that intensity and O max typically have the strongest associations with alcohol, cannabis, and tobacco use variables (e.g., González‐Roz et al, 2019; González‐Roz et al, 2022; Martínez‐Loredo et al, 2021). Finally, our review revealed differences in the extent to which specific demand indices were reliable or valid.…”

“…We recognize behavioral economists have also been concerned with the predictive validity (e.g., MacKillop & Murphy, 2007;Murphy et al, 2015) and concurrent validity (e.g., Gonz alez-Roz et al, 2019;Gonz alez-Roz et al, 2022;Martínez-Loredo et al, 2021). Though important, these topics exceed the scope of our review.…”

Executive functions and behavioral economic demand for cannabis among young adults: Indirect associations with cannabis consumption and cannabis use disorder.

“…Although behavioral economic demand for cannabis is a robust predictor of cannabis consumption and CUD severity (Aston & Berey, 2022; Aston et al, 2015; González-Roz et al, 2022), few studies have examined factors that are associated with individual differences in cannabis demand. This is the first study to our knowledge to examine associations between EFs (i.e., inhibitory control, set shifting, working memory) and indices of cannabis demand.…”

“…Five related indices of behavioral economic cannabis demand may be obtained from the MPT: intensity (i.e., cannabis consumption at zero cost), O max (i.e., peak expenditure on cannabis), P max (i.e., price corresponding to peak expenditure on cannabis), breakpoint (i.e., the cost at which cannabis consumption is suppressed to zero), and elasticity (i.e., the sensitivity of consumption to cost, or the degree to which consumption of cannabis decreases as price increases; Aston et al, 2015; Collins et al, 2014). These demand indices, and especially O max , intensity, and elasticity, are robustly associated with patterns of cannabis use, including quantity and frequency of use, craving, and symptoms of CUD, in a variety of populations including young adults (Aston & Berey, 2022; Aston et al, 2015; González-Roz et al, 2022; Minhas et al, 2021; Strickland et al, 2017; Zvorsky et al, 2019).…”

Prices of flower and resin in cannabis social clubs: Analyses of register data from 220,000 collections

“…Given that lower prices of cannabis products may constitute a potential incentive for increased purchases, especially for high‐risk users [10], it is of interest how cannabis prices are regulated in CSC. Analysing a unique cross‐sectional data set from CSC in Barcelona, Spain, this study was guided by the following research questions: How do cannabis prices in CSC in Barcelona compare to national estimates (from the illicit market)? Can quantity discounts be observed in CSC? …”