Changes

* Make up an Experiment Secret (ES), this is some random string that you store with the experiment. Keep it secret for your participants.

* Make up an Experiment Secret (ES), this is some random string that you store with the experiment. Keep it secret for your participants.

* Store an anonymous Participant Number (PPN) with the data that is related to a certain participant. This participant number can for instance be the token that you use in Limesurvey. It must be unique to the participant and it must not contain information that you cannot give to the participant. It is ok if the PPN is just the participant serial number (1, 2, 3, ...)

* Store an anonymous Participant Number (PPN) with the data that is related to a certain participant. This participant number can for instance be the token that you use in Limesurvey. It must be unique to the participant and it must not contain information that you cannot give to the participant. It is ok if the PPN is just the participant serial number (1, 2, 3, ...)

* Calculate a Participant Identification Code for each participant. If you give the participant your contact information, the name of the experiment, the PPN and their PIC, they will be able to prove that they participated in your experiment and you can identify the data that they supplied. Especially if your PPN has a fixed length you can give them a concatenation of PPN and PIC. If for instance the PPN is 1234 and the PIC is A3D444 then you simple send them the following text:

* Calculate a Participant Identification Code for each participant. If you give the participant your contact information, the name of the experiment, the PPN and their PIC, they will be able to prove that they participated in your experiment and you can identify the data that they supplied. Especially if your PPN has a fixed length you can give them a concatenation of PPN and PIC. If for instance the PPN is 1234 and the PIC is A3D4 then you simple send them the following text:

''Dear Participant,''

''Dear Participant,''

''Thank you for participating in my experiment 'The Role of Squares and Circles in modern Society'.

''Thank you for participating in my experiment 'The Role of Squares and Circles in modern Society'.

Your data was stored anonymously. If you ever want to contact me about the data you supplied,  

Your data was stored anonymously. If you ever want to contact me about the data you supplied,  

please use the code 1234A3D444. I myself have no way of linking you to your data without this code.''

please use the code 1234A3D4. I myself have no way of linking you to your data without this code.''

''Kind regards,''

''Kind regards,''