RTs are responsible for hosting the experimental software and for providing the project coordinators (PCs) with:

1. One anonymous link per experimental treatment to be sent to participants via Prolific.
2. Access to the server on which the experimental software is hosted such that PCs are able to retrieve the data.

Also note that the experimental software has to be compatible with Prolific – i.e., it has to be possible to ...

1. ... send participants to the experiment using an anonymous link,
2. ... record their Prolific IDs, and
3. ... redirect them back to Prolific upon completion.

We, the project coordinators, need access to the server in the sense that we need to be able to access and download all the resulting, original data from all individual experiments. For oTree, for example, this means we need access to the oTree admin interface (i.e., where you set up a session and are able to export the data). If you are using Qualtrics, for example, you need to give us access to your Qualtrics survey so we can access the data there.

Participants will be invited from a selection of the Prolific database which is defined as follows: (a) fluency in English, (b) approval rate above 90%. The participants who accept the invitations will be randomly allocated to the individual studies.

No, we, the project coordinators, will add one on a general welcome screen (the same for all studies).

We will implement a CAPTCHA task to all studies on a general welcome screen and exclude those that answer this incorrectly before randomizing participants to individual studies.

You can include additional attention check questions etc, but these can only be used to exclude participants ex-post, i.e. after participants have completed the experiment.

Please add a question to your study which simply asks participants for their Prolific ID (see 'Adding a question in your study' here; please do not automatically record Prolific IDs via URL parameters in this study).

On Prolific, it is important to redirect participants back to a Completion URL, or provide them with a completion code.
You can either ...

• ... redirect participants automatically to the Completion URL (or have participants click a button to be redirected), or
• ... manually include the Completion URL / Completion Code at the end of the study and ask participants to copy and paste the code into Prolific.

See here for more information.
The Completion URL / Completion Code will be provided by the project coordinators (PCs).

No. Each RT will have to provide one anonymous link per experimental treatment, i.e. two links. The randomization will be done by the project coordinators for all studies.

No, research teams are responsible for hosting the experimental software and for providing the project coordinators (PCs) with one anonymous link per experimental treatment to be sent to participants via Prolific, and with access to the server on which the experimental software is hosted such that PCs are able to retrieve the data (see software). The PCs cover fixed payments of GBP 1.30 for all participants and, on top of that, as well as participants’ bonus payments up to GBP 680 in total only (i.e., an average bonus of GBP 1.70 for 400 participants).

The deadline for submitting the software is Friday, October 1st.
Please prepare the following materials and send them to [email protected] for submitting your software:

• One anonymous link per experimental treatment to be sent to participants via Prolific.
• Access to the server on which the experimental software is hosted such that PCs are able to retrieve the data.

Yes, grouping participants into small groups is possible. Of course, however, it is up to the research teams (RTs) to figure out the details on how to exactly implement it in their software (e.g., waiting rooms, etc.). The project coordinators will allocate the participants to the RTs’ different software solutions and then it is up to the RTs to form groups if needed. To ensure feasibility, we recommend considering small group sizes (if any) as well as time-outs to avoid participants getting stuck waiting for other participants in their group.

Yes, this is possible.

No. However, the project coordinators we will only recruit Prolific participants with English fluency and an approval rate of 90% or higher.