Hi,

I have 100 questions and want to randomly select 30 of them for each participant. Each question is on a separate page, containing 2 sliders. For example:
In this situation:
How likely is it (7 points scale)
How often (7 points scale)

I'm wondering if I can put sliders in trials and randomly select or in the surveypage.

Thank you

A <surveypage> is a special kind of <trial>, so assuming you have 100 surveypages and want to randomly select 30 of those, you can do

<block example>
/ trials = [1-30 = noreplace(pg1, pg2, pg3, pg4, ..., pg99, pg100)]
</block>

Thank you, Dave. I was doing this but I'm wondering if there is easier way to do it because each page contains 1 question with the same 2 scales, it's only the question that is different. 

You can also do something like this (example uses 3 questions out  of 10):

<block myblock>
/ trials = [1-3=mypage]
</block>

<surveypage mypage>
/ stimulusframes = [1=myquestion]
/ questions = [1=question; 2=slider1; 3=slider2]
/ showpagenumbers = false
/ showquestionnumbers = false
</surveypage>

<text myquestion>
/ items = myquestions
/ position = (-10%, 10%)
/ fontstyle = ("Arial", 0%)
/ size = (0%, 0%)
/ select = noreplace
</text>

<item myquestions>
/ 1 = "Question A"
/ 2 = "Question B"
/ 3 = "Question C"
/ 4 = "Question D"
/ 5 = "Question E"
/ 6 = "Question F"
/ 7 = "Question G"
/ 8 = "Question H"
/ 9 = "Question J"
/ 10 = "Question K"
</item>

<caption question>
/ caption = "<%text.myquestion.currentitem%>"
</caption>

<slider slider1>
/ range = (0, 10)
</slider>

<slider slider2>
/ range = (0, 10)
</slider>