how to show participants 12 randomly chosen videos out of a set of 40 videos in random order for three within conditions

Question

Hello everyone,

I have three within conditions which consist of different videos. Each participant has to watch videos from all three within conditions. Each within condition contains 40 videos and each participant should watch 12 videos per condition. I therefore need a function that will randomly show 12 out of the 40 videos from each condition (so 36 Videos in total per participant) - but not all videos from one condition in a row but rather also randomly chosen from each within condition.

Can I somehow use the "random generator" function for this or do I have to tackle the problem differently?

Thank you so much for your time and input!

Best

Answer 1

Okay, first you'll need three random generators that draw 12 items per interview, each. Use them in the questionnaire and you know which videos to display.

In the easy case, create 3 times 12 pages for the videos plus the questions do display after each set. We could as well work with loopPage() to do it with one page per condition, but it's really hard to get that working together with setPageorder() for the condition order.

So, if your random generators are names RG01, RG02 and RG03 and the video filenames are stored in the generators (as items), the video-pages will contain a PHP code like this:

replace('%videofile%', 'RG01x1', 'response');

And on the second page in condition 1

replace('%videofile%', 'RG01x2', 'response');

Up to the the 12th video in the third condition

replace('%videofile%', 'RG03x12', 'response');

Below that PHP code, you'll need the HTML code to display the video (HTML 5), and just replace the filename by the placeholder %videofile%.

When that works, give the first an last page in each set (12+x) a page ID and before the first page, use the PHP code as described here: Rotation of Question Blocks.

Finally, if you need the order of the three conditions, read on here: put () Funktion um Rotation festzuhalten (you'll need either code (1) or (2).

Comments

Thank you very much for your help. I was able to display the videos. 12 videos are drawn and than displayed on 12 different pages however, it only saves the answer for the first question. When the participants get to the second question it overrides the first answer.

I do not fully understand the ID concept etc. - could you elaborate?

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> it only saves the answer for the first question

You must display a different question or a different item from the same question for each video. And it should be the same question for the same video, each time. I suggest, you post your full PHP code in a new question. Than we can go on the second part. Please also describe what kind of question you display for each video.