Consistency of self-reported alcohol consumption on randomized and sequential alcohol purchase tasks

Abstract

Behavioral economic demand for addictive substances is commonly assessed via purchase tasks that measure estimated drug consumption at a range of prices. Purchase tasks typically use escalating prices in sequential order, which may influence performance by providing explicit price reference points. This study investigated the consistency of value preferences on two alcohol purchase tasks that used either a randomized or sequential price order (price range: free to $30 per drink) in a sample of 91 young adult monthly drinkers. Randomization of prices significantly reduced relative response consistency (p < 0.01), although absolute consistency was high for both versions (>95%). Self-reported alcohol consumption across prices and indices of demand were highly similar across versions, although a few notable exceptions were found. These results suggest generally high consistency and overlapping performance between randomized and sequential price assessment. Implications for the behavioral economics literature and priorities for future research are discussed.

Keywords: alcohol; behavioral economics; consistency; demand; purchase task.

Figure 1

Self-reported alcohol consumption by price across sequential (APT-Seq; dark gray bars) and randomized (APT-Rand; light gray bars) versions. Individual bars represent mean (±standard error). Note, N = 91; *p < 0.05; **p < 0.01.

Figure 2

Indices of alcohol demand across sequential (APT-Seq; dark gray bars) and randomized (APT-Rand; light gray bars) versions. (A) Depicts intensity of demand. (B) Depicts square-root transformed breakpoint. (C) Depicts square-root transformed O_max. (D) Depicts square-root transformed P_max. (E) Depicts logarithmically transformed elasticity (α). Individual bars represent mean (± standard error). Note, N = 91; ***p < 0.001.