Table 3 Summary of findings from the studies that use a Marijuana Purchase Task
From: Characteristics that influence purchase choice for cannabis products: a systematic review
Authors—year | Number of prices | Prices (per unit) | Cannabis unit | Demand equation | Significant demand predictors | Summary of results |
|---|---|---|---|---|---|---|
Price elasticity | ||||||
Amlung and MacKillop—2019 | 20 | free, $1, $2, $4, $6, $8, $10, $12, $14, $16, $18, $20, $25, $30, $35, $40, $45, $50, $55, and $60 | Dried flower (grams) | Not reported | Intensity Price elasticity Pmax | - Illegal cannabis: elasticity = 0.0042 (alone), 0.0095 (with legal alternative); Pmax = 14.09 (alone), 8.22 (with legal alternative); intensity Q0= 9.11 (alone) - Legal cannabis: elasticity = 0.0029 (alone), 0.0046 (with illegal as alternative); Pmax = 16.28 (alone), 9.65 (with illegal as alternative); intensity Q0= 11.20 (alone) - Both are inelastic, but illegal cannabis is more elastic - Having legal cannabis as an alternative had a greater effect on the elasticity of illegal cannabis than vice versa (threefold difference). - Sensitivity analyses revealed that the asymmetric substitution pattern for legal over illegal cannabis was identical across genders, age, and income demographics |
Amlung et al.—2019. | 20 | Free, $1, $2, $4, $6, $8, $10, $12, $14, $16, $18, $20, $25, $30, $35, $40, $45, $50, $55, $60 | Dried flower (grams) | Nonlinear exponential demand curve model—(Hursh and Silberberg (2008) Exponential cross price elasticity model (Hursh, 2014) | Intensity Pmax Price elasticity Substitutability | - Illegal cannabis: elasticity = 0.0028 (alone), 0.0047 (with legal alternative); Pmax = 9.41 (alone), 6.16 (with legal alternative); intensity Q0= 11.01 (alone) - Legal cannabis: elasticity = 0.0016 (alone), 0.0018 (with illegal alternative); Pmax = 11.67 (alone), 10.74 (with illegal alternative); intensity Q0=15.55 (alone) - Both are inelastic, but illegal cannabis is more elastic, showing greater price sensitivity for illegal cannabis - Substitution: indicated as present with both fixed-price alternatives having significant positive linear cross-price elasticities (slope of illegal alternative significantly > legal alternative) - All demand indices demonstrated asymmetrical substitutability with the presence of the legal alternative increasing the elasticity of illegal cannabis to a greater degree than the reverse |
Aston et al.—2015 | 22 | $0, $0.25, $0.50, $0.75, $1, $1.25, $1.50, $1.75, $2, $2.50, $3, $3.50, $4, $4.50, $5, $5.50, $6, $6.50, $7, $8, $9, $10 | Average quality hit of cannabis (assume 10 hits of cannabis in a joint; 1 joint = 1/32nd of an ounce = 0.9 g) | Nonlinear exponential demand curve model—Hursh and Silberberg (2008) | Intensity Omax Pmax Breakpoint Price elasticity | - Intensity Q0: 23.71 - Omax: 16.13 - Pmax: 2.32 - Breakpoint: 4.24 - Elasticity: 0.04 - Income was not associated with demand |
Aston et.al—2016 | 22 | $0, $0.25, $0.50, $0.75, $1, $1.25, $1.50, $1.75, $2, $2.50, $3, $3.50, $4, $4.50, $5, $5.50, $6, $6.50, $7, $8, $9, $10 | Average quality hit of cannabis (assume 10 hits of cannabis in a joint; 1 joint = 1/32nd of an ounce = 0.9 g) | Nonlinear exponential demand curve model—Hursh and Silberberg (2008) | Intensity Omax Pmax Breakpoint Price elasticity | - Intensity Q0: 24.94 - Omax: 16.03 - Pmax: 2.31 - Breakpoint: 4.27 - Elasticity: 0.05 |
Collins et al.—2014 | 16 | $0/free, 10¢, 25¢, 50¢, $1, $2, $4, $5, $7.50, $10, $15, $20, $30, $40, $80, and $160 | Average-sized joint of high-grade cannabis | Modified version of the non-linear mixed effects model proposed by Hursh et al. (1998) | Intensity Breakpoint Price elasticity | - Intensity = ~ 10 joints when price was free - Omax: 46.63 - Pmax: 13.21 - Breakpoint = $38.07 - Elasticity = − 1.75 (elastic); demand inelastic across low prices $0/free to $13/joint, but elastic for higher prices of $15 to $160/joint |
Hindocha et al.—2017 | 23 | £0, 1p,2p, 5p, 10p, 15p, 20p, 30p, 40p, 50p, 75p, £1, £1.50, £2, £2.50, £3, £3.50, £5, £5, £7.5, £10, £15, £20 | Puff of cannabis | Exponentiated demand equation (Koffarnus et al. 2015) | Intensity Omax Pmax Breakpoint Price elasticity | - Intensity Q0: 17.14 - Omax: 652.95 - Pmax: 92.19 - Breakpoint: 145.29 - Elasticity: 0.61 (when compared to placebo, cannabis was more sensitive to price) |
Nisbet and Vakil—1972 | Unknown | Unknown | Lids (ounces) of dry flower | Double log function | Price elasticity Expenditure elasticity | - Price elasticity = − 0.365 - Expenditure elasticity = − 0.311 |
Patel et al.—2019 | 20 | $0–$60 (specific prices not reported) | Dried Flower (grams) | Nonlinear exponential demand curve model— Hursh and Silberberg (2008) | Intensity Omax Pmax Breakpoint Elasticity | - Non-DACU intensity Q0: 8.51 - Non-DACU Omax: 54.80 - Non-DACU Pmax: 15.22 - Non-DACU breakpoint: 22.24 - Non-DACU elasticity: 0.004 - DACU intensity Q0: 13.81 - DACU Omax: 98.92 - DACU Pmax: 16.65 - DACU breakpoint: 29.83 - DACU elasticity: 0.002 Note: This study compared demand for individual who reported Driving after cannabis use (DACU) and those who did not |
Peters et al.—2017 | 9 | $0.01, $0.03, $0.10, $0.30, $1.00, $3.00, $10.00, $30.00, $1000.00 | Puff of cannabis | Nonlinear exponential demand curve model—Hursh and Silberberg (2008) | Price elasticity | - Price elasticity: 0.0044 (95% Cl 0.0038, 0.0049) - Price elasticity did not change by gender, but was slightly different based on nicotine dependence. Both groups still showed inelastic behavior |
Strickland, et al. -2017 | 13 | $0–$11 (specific prices not reported) | Hits of cannabis (hits—10 hits/joint with 1 joint equal to 0.9 g of cannabis) | Exponentiated demand equation (Koffarnus et al. 2015) | Intensity Elasticity | - Intensity Q0: 35.6 - Elasticity: 0.028 |
Strickland et al.—2019 | 17 | $0.00 (free), $0.25, $0.50, $1, $1.50, $2, $2.50, $3, $4, $5, $6, $7, $8, $9, $10, $15, $20 | Hits of cannabis (hits—10 hits/joint with 1 joint equal to 0.9 g of cannabis) | Exponentiated demand equation (Koffarnus et al. 2015) | Intensity Omax Pmax Breakpoint Elasticity | - Intensity Q0: 37.15 - Omax: 16.22 - Pmax: 1.55 - Breakpoint: 3.98 - Elasticity: 0.007 *Note: the paper presented log transformed values, these have been reverted back for easier comparison |
Teeters et al. 2019 | 20 | $0.00—$10.00 (specific prices not reported) | Hit of cannabis (10 hits of cannabis in a joint with 1 joint equaling to 1/32 of an ounce or 0.9 g) | Exponentiated demand equation (Koffarnus et al. 2015) | Intensity Omax Pmax Breakpoint Price elasticity | - Intensity Q0: 24.41 - Omax: 11.93 - Pmax: 1.59 - Breakpoint: 3.31 - Elasticity: 0.06 |
Vincent et al.—2017 | 9 | Free ($0), $2.50, $5.00, $7.50, $10, $12.50, $15, $17.50, and $20 | Low-grade, medium-grade, and high-grade joints (an average sized joint was defined as approximately 0.5 g, 5 bong hits, or 10 puffs) | Nonlinear mixed effects modeling (Pinheiro and Bates, 2000) | Intensity Omax Pmax Breakpoint Price elasticity | - Intensity Q0 (derived): low-grade = 4.56; medium-grade = 5.06; high-grade = 5.85 - Omax (derived): low-grade = 8.53; medium-grade = 13.57; high-grade = 19.49 - Pmax (derived): low-grade = 5.08; medium-grade = 7.28; high-grade = 8.99 - Breakpoint: low-grade = 7.17; medium-grade = 9.86; high-grade = 13.10 - Elasticity: low-grade = −1.97; medium-grade = −1.37; high-grade = −1.11 (when the log transformation is reversed, elasticity values are 0.011, 0.043, and 0.078 respectively) - Note: Values in this study were square-root or log transformed. |
Quality elasticity | ||||||
Cole et al.—2008 | Cash on hand/income—fixed at 1 level | £40 | All dry flower: poor, average, and good quality. All £15 per 1/8 oz. (3.5 g). | Not specified | Quality Elasticity | - Quality elasticity: − 1.31 - There were significant correlations between the self-reported number of cannabis joints used per episode and purchases of cannabis in the average and good quality conditions, but not in the poor-quality condition - As quality of cannabis decreased so did purchases for average and poor quality cannabis compared to good per individual. The number of individuals purchasing cannabis also decreased |
Goudie et al.—2007 | Cash on hand/income—8 levels | £20, £25, £30, £35, £40, £45, £50, £55 | All dry flower: poor quality: £10 per 1/8 oz. Average quality: £15 per 1/8 oz. Good quality £20 per 1/8 oz. | Not specified | Income elasticity over different levels of quality | - Income elasticity: poor quality (− 0.21); average quality (1.16), good quality (3.14) over all income levels - Significant interaction between quality and income for the number of units purchased - Number of respondents purchasing at least a single unit of cannabis at each income level increased significantly for good quality cannabis. |