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Task 2 - Comprehension Questions on Belief Elicitation



Please answer below the comprehension questions about the belief elicitation mechanism.

You will not be able to proceed until you answer all of them correctly.

If you find any difficulties answering the questions please refer back to the instructions located below the “next” button.

If you have any questions or doubts, please raise your hand.

{% formfield player.Task2aCQ1 label="The belief payment mechanism ensures that it is optimal to state your true belief (probability) that the event occurred." %} {% formfield player.Task2aCQ2 label="If you believe the probability that it rained yesterday in New York is 50%. What belief should you state in order to have the highest chance to win the £6.00?" %} {% formfield player.Task2aCQ3 label="Out of the belief questions you will be asked for this part of the experiment, how many will be paid?" %}

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Reminder: Instructions' Task 2 (Belief Elicitation)



In this task, we will ask your beliefs regarding the probabilities of some events. The probabilities you state will affect your payment in this experiment. In particular, the payment method is such that you have the highest chance of earning (more) money by stating the true probability with which you think the event will occur.

We will now explain you how the payment method works. For ease of understanding, let us consider a specific event: The probability that it rained yesterday in New York. Note that this example is only for illustrative purposes, in the experiment it will be replaced by other events.

We give you £6.00 and you have to decide whether you want to place your bet on the lottery or the event:

Should you place your bet on the lottery or the event (to have the highest chances of earning the £6.00)? This will depend on the number of purple balls in the urn and the probability you think it rained yesterday in New York.

For example, if there are 5 purple balls in the urn, the chance to win the £6.00 by picking the lottery is only 5%. Hence, most people would choose the event since the chance that it rained in New York is probably higher than 5%. However, if there are 90 purple balls in the urn, picking the event will only give you a higher chance to win the £6.00 if you believe the probability that it rained in New York is higher than 90%. Therefore in this case most people would pick the lottery.

How are you going to place your bet?

We will ask you to state your belief regarding the probability with which the event occurred. The mechanism ensures that it is optimal for you to state your true belief. In particular, this is because the number you give determines how many purple balls need to be there (in the lottery) for you to prefer to place your bet in the lottery instead of the event. The computer will then determine the composition of the urn. If there happen to be fewer (or equally many) purple balls than the minimum you chose, you will be betting on the event. Thus, you will earn £6.00 if it rained yesterday in New York and £0.00 otherwise. If there happen to be more purple balls than the minimum you chose, you will be betting on the lottery. Then the computer draws a ball. If the ball drawn is purple, you earn £6.00, if the ball is orange you earn £0.00. This method guarantees that you have the highest chances of earning the £6.00 if you report your true belief of the event occurring (if you wish, below the "next" button you can find a more detailed explanation of why this is the case).

While this method may look complicated, its implications are simple: you have the highest chance of earning (more) money if you honestly report your best guess of the probability of the event occurring. For example, if you believe that it rained yesterday in New York with 80%, you should state 80%.


Task 2: Payment


In this task, we will ask you four belief questions. Out of the four, the computer will randomly draw one. The randomly drawn question will count for your payments (if this task is selected to count for payments). In particular, you will be paid for your answer in that question following the method explained here.

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