Interpretation(s) of elasticity in operant demand

Gilroy et al. (2020) wrote a map of the word "elasticity." They looked at how BCBAs use three numbers: plain elasticity, Essential Value, and PMAX. The paper shows each number measures a different curve feature. It tells us to stop swapping the words like they mean the same thing.

The authors used math, not new data. They drew demand curves and labeled the exact spots each index captures.

Elasticity (η) is only the slope of the demand curve at one price. Essential Value is the whole area under the curve. PMAX is the single price where spending peaks.

Calling all three "elasticity" mixes apples, oranges, and bananas.

Axe et al. (2021) did the same clean-up job for the term "discriminative stimulus." Both papers yell, "Stop sloppy labels!" They share the same mission but fix different words.

Burgio et al. (1991) warned us first. That older paper said we fight over what "reinforcer" and "discriminative stimulus" even mean. Gilroy et al. (2020) picks up the torch and adds elasticity to the list of messy terms.

Simó-Pinatella et al. (2013) reviewed 31 studies that use demand curves. Their review sits in the same assessment world but never fixed the math labels. Gilroy fills that gap.

Next time you graph a reinforcer assessment, write η for slope, not "elasticity" for everything. Clear labels help teams read your graph the same way. One word, one meaning, fewer fights over data.