We introduce to behavior analysis a way of analyzing choice behavior that exploits recent developments in nanoeconomics, financial economics, and econometrics. A response return, modeled on an economic return, is the log differenced count of responses allocated to each of two alternatives during a short time window, compared with that in the immediately preceding window. The response return is a new dependent variable which offers a novel and useful way of looking at operant behavior, especially at the molecular level of analysis. The response–return series is a near‐instantaneous measure of an organism's dynamic preferences for each of two alternatives. Analyzing such a series requires time‐analytic techniques, including Auto‐Regressive Conditional Heteroskedastic (ARCH) models. We illustrate these techniques by analyzing choices between combinations of arithmetic and exponential variable‐interval schedules with pigeon subjects. All response–return series were well‐fitted by one of three ARCH‐family models. The fitted models were differentially sensitive to transition versus steady‐state data samples. The particular insights that the ARCH analyses offer are improved understanding of the effects of the instantaneous effects of reinforcers and their absence, of how the distribution of reinforcers in time affects choice, and of the differences between choice in transition and at steady state.