Morgan Grant edited this page Sep 19, 2017 · 1 revision

Paying Subjects

With the goal of making payments to subjects at the end of an experiment a smooth and seamless experience, ConG offers a number of options for converting the points subjects earn in the experiment into a cash amount. The experimenter does this via the "Show Payout Table" feature in the Control window. If case it's useful, ConG also creates a "payout.csv" file logging all points earned per period per subject as well.

Paid vs. Unpaid Periods - First, experimenters designate whether or not a particular period is paid or unpaid in the config file. This can be useful if it's desirable to have practice or pilot periods in an experiment. In unpaid periods, subjects are free to familiarize themselves with the interface and game without worrying about the effect of this practice on their cash payments. Only periods marked paid==TRUE (see config file screen capture below) have their points inputted into the Payout Table. Unpaid periods are excluded from the payout table.

In the config file screen capture below, periods one and two are unpaid while the remaining periods are all paid.

Show-up fee - The show-up fee is the cash amount paid to all subjects, irrespective of points earned. This amount will be added to all subjects' cash total in the payout table.

Threshold - Threshold refers to the number of points above which the payout table is to convert into cash. For example, suppose a subject earned 100 points during an experiment. If the threshold is set to 75, then only the remaining points, 25 points, are converted into a cash amount by the payout table.

Sometimes total points do not vary much between subjects. The threshold feature may be a useful way of increasing the variance of cash payouts. However, ensure that the threshold is not set too high, since it is possible to have negative payouts if threshold is above a subject's earnings.

Conversion Rate - This is the rate at which points, above the threshold, are converted into a cash amount.

Thus the payout table takes, for each subject, total points earned in paid periods, subtracts the threshold amount, multiplies this by the conversion rate, and adds the show-up fee.

Figure - The figures above show the payout table with two different threshold and conversion schemes, which deliver different cash payout amounts.


If your payment scheme relies on some system not supported by the Payout Table, the payout.csv log will give a period by period account of points earned by each subject. An example of this CSV file, placed next to the control.jar file that ran the experiment, appears below.

Linux Users and payouts.csv - If you use Linux, your output files (payouts.csv, Ticks, client_errors, server_errors, and ip_address) will be placed into the Home directory.

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