Frequently Asked Questions

You can complete the registration form here:

Students who register can be invited to GrEELab experiments, and they can then decide for each experiment whether they want to participate. Each invitation will mention how much money students can earn in that experiment, and where (e.g. in our lab or online) and when the experiment will take place.

GrEELab stands for: Groningen Experimental Economics Laboratory. As the name suggests, it is a lab whose main purpose is to host economic experiments. 

Students can earn money by participating in GrEELab experiments (see details later in this document). Participation also benefits science, because it enables researchers to conduct studies (without participants, we cannot run experiments).

During a typical GrEELab experiment you sit in front of a computer and conduct some tasks or make a choice between specific options. Importantly, you get paid for the tasks that you do or the choices that you make. The experimental instructions will always explain what you need to do and how the magnitude of your earnings depend on the things that you do. No prior knowledge is required to participate.

Every experiment is different, but on average an experiment will last for 1 or 2 hours. The invitation for the experiment will always indicate how long the experiment will take.

Payments will happen via FedRbp, which is the official secure payment system of the university. If you didn't register your bank account number in Fedrbp yet, you can do so after logging in with your RUG account on this page:

Note that only people with RUG accounts can use the Register / SignIn with an UG account option on the top right corner of the FedRbp page. Those who do not have a RUG account need to create an external Fedrbp account on the top left corner instead.

Note: GrEELab and the FedRbp system are separate from each other and we cannot register you in FedRbp, you need to do that yourself. FEDRbp requires an IBAN from the SEPA region. This includes all EU countries with a few additions. In case of a Dutch bank account number the Fedrbp system will ask for your BSN number as well (again, the Fedrbp system is separate from GrEELab, so such details are not shared with us).

FedRbp was updated in 2022, so if you registered there before 2022 then you will have to update your FedRbp registration to receive payments.

If you complete an experiment, GrEELab will instruct Fedrbp to pay you the exact amount that was promised to you during the experiment. The magnitude of that amount depends on the specifics of the experiment. For example, it can depend on the length of the experiment, on performance in a task, on participants' choices, or on other elements such as a lottery. The average payment is typically 12-13 euros per hour. This is an average, which means that your earnings could be considerably more, or somewhat less (there is typically a minimum amount, which will be mentioned in the invitation).

Each invitation will mention how much money participants are expected to earn on average in that experiment, and you can then decide whether you want to enroll for that particular experiment. During the experiment the instructions will explain how your earnings are determined (e.g. how much you get for a certain performance in a task, what are the probabilities of winning a lottery, and so on). Your payment will always be in line with the instructions.

First of all, you need to complete your registration by filling in the registration form.

After you are registered, you may receive invitations for experiments. If you are invited to an experiment, you will see which time-slots are available for that experiment and you can enroll yourself for the one that fits you most.

Our lab is on the ground floor of the Duisenberg building, in room 5412.0014, just beside the entrance that is facing the Kapteynborg. Unless otherwise mentioned, this will be the location of our experiments. The invitation to the experiment will always explicitly mention if the location is somewhere else (e.g. online).

You can participate in every experiment to which you are invited, and you can participate in each of them once. So if you participated in one of our experiments, you can still participate in another one of our experiments, just not in the same one.

You do not have to worry about this, we take care of eligibility. So if you receive an invitation, feel free to enroll on the corresponding Brightspace page. After you participated in the experiment(s) to which you were invited, we remove you from the corresponding Brightspace page(s), so that you cannot accidentally participate again in the same experiment. We may add you to another page if there is another experiment, in which you can also participate, and so on.

FedRbp is the official automated payment system of the university via which we have to pay research participants. GrEELab is not allowed to hand out cash, we have to put payment instructions in FedRbp, such that the system sends the money to the participants' bank account.

Since the university obliges GrEELab to pay via FedRbp, you need to register in FedRbp to be able to receive payments. If you encounter a technical problem with FedRbp, please contact the CIT servicedesk ( ). Note that GrEELab is only a user of FedRbp, similarly to you, so we cannot fix technical problems ourselves.

Note that FEDRbp requires an IBAN from the SEPA region. This includes all EU countries with a few additions. In case of a Dutch bank account number the system will ask for your BSN number as well.

To register in FedRbp, please visit

Note: FedRbp was updated in 2022, so if you registered there before 2022 then you will have to update your FedRbp registration to receive payments.

GrEELab obliges its researchers to keep their promises, so the experimenters have to make sure that everything that they say to participants is true. This holds not only for the magnitude of the payments, but also more generally.

For example, if the experimental instructions state that you are paired with another participant for a certain task then the experimenter has to make sure that this is indeed the case. Another example is that if the instructions describe a lottery then the experimenter has to make sure that the lottery is conducted with the exact probabilities that were told you in the instructions.

Yes, your participation in an experiment is voluntary and you can leave any time. However, if you leave without completing the experiment you will not be paid for your participation.

One reason could be that you did not fill in the Registration Form and therefore your registration is not complete yet.

Another reason could be that only a subset of people were invited to participate in that experiment. This is not a mistake, the list of invitees can vary from experiment to experiment. 

If you are not invited to a specific experiment, you can not participate in that experiment. You may, however, be invited for another experiment. 

You can deregister from the participant registry by sending an email to in which you explain that you want to do this. In this email you can also indicate whether you want to delete the information that you provided via the Registration Form.

If your question is not answered above, you can send an email to