The Decisions Prediction Competition

A total of 160 Technion students participated in the estimation study. Participants were paid 40 Sheqels ($11.4) for showing up, and could earn more money or lose part of the show-up fee during the experiment. Each participant was randomly assigned to one of the three experimental conditions: Description, E-sampling, and E-repeated (Feedback).

Each participant was seated in front of a personal computer screen and was presented with a sequence of choice tasks. The exact tasks depended on the experimental condition as explained below. The procedure lasted about 40 minutes on average in all three conditions.

The payoffs on the experimental screen in all conditions referred to Israeli Sheqels. At the end of the experiment one problem was randomly selected and the participant’s choice in that problem determined his/her final payoff.

The 60 choice problems described in section 4 (the estimation set) were studied under all three conditions. The main difference between the three conditions was the source of the information (description, sampling or feedback). Yet, the manipulation of this factor implied other differences. The unique properties of the experimental method in each of the three conditions are described below:

Twenty Technion students were assigned to this condition. Each participant was seated in front of a personal computer screen and was then presented with each of the 60 problems specified in the estimation set. Participants were asked to choose once between the sure payoff and the risky gamble in each of the 60 problems that were randomly ordered.

This experiment includes several games. In each game you will be asked to select one of two alternatives.

At the end of the experiment one of the games will be randomly drawn (all the games are equally likely to be drawn), and the alternative selected in this game will be realized.

Forty Technion students participated in this condition. They were randomly assigned to two different sub-groups. Each sub-group contained 20 participants who were presented with a representative sample of 30 problems from the estimation set (each problem appeared in only one of the samples, and each sample included 10 problems from each payoff domain). The participants were told that the experiment includes several games, and in each game they will be asked to choose once between two decks of cards (represented by two buttons on the screen). It was explained that before making this choice they will be able to sample the two decks. Each game was started with the sampling stage, and the participants were asked to press the "choice stage" key when they felt that they have sampled enough (but not before sampling at least once from each deck).

The outcomes of the sampling were determined by the relevant problem. One deck corresponded to the safe alternative: All the (virtual) cards in this deck provided the medium payoff. The second deck corresponded to the payoff distribution of the risky option; e.g., sampling the risky deck in problem 21 resulted with the payoff “+2 Sheqels” in 10% of the cases, and outcome “-5.7 Sheqels” in the other cases.

At the choice stage participants were asked to select once between the two virtual decks of cards. Their choice yielded a random draw of one card from the selected deck and was considered at the end of the experiment to determine the final payoff.

This experiment includes several games. Each game includes two stages: The sampling stage and the choice stage.

At the choice stage (the second stage) you will be asked to select once between two virtual decks cards (two buttons). Your choice will lead to a random draw of one card from this deck, and the number written on the card will be the "game's outcome."

During the sampling stage (the first stage) you will be able to sample the two decks. When you feel that you have sampled enough press the "choice stage" key to move to the choice stage.

At the end of the experiment one of the games will be randomly drawn (all the games are equally likely to be drawn). Your payoff for the experiment will be the outcome (in Sheqels) of this game.

One hundred Technion students participated in this condition. They were randomly assigned to five different sub-groups. Each sub-group contained 20 participants who were presented with (each problem appeared in only one of the samples, and each sample included 10 problems from each payoff domain). Each participant was seated in front of a personal computer and was presented with each of the 12 problems for a block of 100 trials. Participants were told that the experiment would include several independent sections (each section included a repeated play of one of the 12 problems), in each of which they would be asked to select between two unmarked buttons that appeared on the screen (one button was associated with the safe alternative and the other button corresponded to the risky gamble of the relevant problem) in each of an unspecified number of trials. Each selection followed with a presentation of its outcome in Sheqels (a draw from the distribution associated with that button, e.g., selecting the risky button in problem 21 resulted with gain of 2 Sheqels with probability 0.1 and loss of 5.7 Sheqels otherwise).

This experiment includes several games. Each game includes several trials. You will receive a message before the beginning of each game.

In each trial you will be asked to select one of two buttons. Each press will result with a payoff that will be presented on the selected button.

At the end of the experiment one of the trials will be randomly drawn (all the trials are equally likely to be drawn). Your payoff for the experiment will be the outcome (in Sheqels) of this trial.

Notice that there were two main differences between the E-sampling and E-repeated conditions: 1. In the E-repeated any trial of the 100 trials could be selected to determine the payoffs. In the E-sampling only the final “choice trial” can be selected to determine the payoff. The other trials are “free sampling trials”

2. In the E-sampling trial the participants determine the number of trials.

3. Experimental Method