[The price-based certainty of purchase influences consumer behavior for discount].

Tversky & Kahneman (1981) reported that most participants decided to drive when they could save money on a low-price good as compared to when they could save on a high-price good, even though the discount prices were same. Although this irrational decision making has been interpreted as a rate-dependent estimation of value (prospect theory), this study newly proposes that it can be explained by the certainty of purchase based on the price of goods. Experiment 1 replicated the previously reported difference in decision making, and additionally demonstrated that participants' certainty of purchase was lower for a high- than a low-price good. When it was emphasized that participants' intention to purchase high- and low-price goods were equally sure, decision making did not significantly differ (Experiment 2). Furthermore, decision making differed based only on the certainty of purchase even,when prices of goods were-same (Experiment 3). Consumers' decision making may be rather rational, depending straightforwardly on the certainty of purchase that is susceptible to price.