Problem with per-trial weight adjustment using setweight

[David McFarlane]

Oh, and if you do come up with a good way of doing on-the-fly 
randomization with constraints in E-Prime, then please, please write 
back and let us know!  This problem has bedeviled many of us for a 
long, long, time.  (Then again, some literature argues that 
randomization with constraints is a Bad Thing in psychology 
experiments, but that is another topic.)

Regards,
-- David McFarlane


At 4/1/2014 10:58 AM Tuesday, David McFarlane wrote:
>Well...  Implementing specific constraints on randomization at 
>runtime gets very tricky, try searching for discussions using terms 
>such as "random", "pseudorandom", "pseudo-random", "constrain", and 
>"constraint".  Offhand, I feel very leery of any approach using 
>List.SetWeight, and I especially hope that you do not try that while 
>the List itself is running!
>
>PST shows one time-honored (though crude) method for implementing 
>on-the-fly randomization with contstraints in their "No Repeats on 
>Consecutive Trials" examples on their website, and you might adapt 
>that approach for your program.  That method, however, is a sort of 
>nondeterministic "bogosort" (look that up on Wikipedia) which 
>suffers several problems.
>
>The cheap answer, which you will find in other discussions, is just 
>to randomize everything before runtime outside of 
>E-Prime.  Construct a "random" sequence that has the properties you 
>seek, then implement that as a Sequential List in E-Prime.  If you 
>want different random orders for different subjects, then construct 
>a few more sequences outside of E-Prime, implement each of your 
>sequences as a nested List (running in Sequential order), and then 
>have E-Prime pick one of those nested Lists on each run (perhaps 
>using a main List set to Counterbalance order).  Or, generate your 
>sequence outside of E-Prime as a properly formatted .txt or .xml 
>file, and then use List LoadMethod "File" to read in the sequence at runtime.
>
>-- David McFarlane
>
>
>At 4/1/2014 08:10 AM Tuesday, LaurensK90 wrote:
>>Now that I have access to E-Basic help again I see that I was 
>>mistaken about the function of List.Reset, and appending this to 
>>the end of the script caused the experiment to create the 
>>appropriate switch ratio. So thank you very much for that suggestion!
>>
>>However, my attempt at preventing the experiment from running more 
>>than five consecutive trials of the same type is still not 
>>effective. I suspect there's something wrong with the way I'm 
>>trying to increment the counter variable, which leads to the second 
>>If statement never getting triggered. Could that be the problem?

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