Randomisation of images in different pages

Question

Hi everyone!

I have a problem with image randomisation.

• I have 4 experimental groups and 2 treatment conditions (set of image and text);
• 2 sets of images with 10 images per set (20 images in total);
• each experimental group I show randomised questionnaire;
• a questionnaire consists of several pages including 3 pages with images and questions about it;
• I want to show 3 random pictures out of 10 images per experimental group/questionnaire.

I already added randomisation for questionnaires (it works) and randomisation for images: 3 codes per interview without returning and sequential assigning (it doesn't work).

The problem is that images repeat in pages and a participant sees not 3 different pictures but 2 same and 1 different (for example). I guess that it counts pictures per page and not per questionnaire.

I hope that I explained well :)

Could anyone suggest a solution for that?

Answer 1

I want to show 3 random pictures out of 10 images per experimental group/questionnaire.

Okay, this is something you can easily tell the random generator. You only need a bit PHP code to actually display the three images, then.

Do you already have some PHP code? Please post it. If not, get a first inspiration here: Texts in the Random Generator and Placeholders.

And to vary the sets of images, you can, of course, draw from different random generators, depending on the group assignment.