Problem with per-trial weight adjustment using setweight

Thu Apr 3 22:09:46 UTC 2014

In their latest e-mail on this subject, PST support told me that "Generally, 
a List cannot be reset while it is running, though it may be that your 
experiment falls into a small set of cases when it will work."

I think I will have to check whether the other properties of the experiment 
are also working as intended, but as far as I could tell, nothing out of 
the ordinary was happening. I did also manage to solve the problem of 
avoiding more than five consecutive repeats: as I suspected, the problem 
was that the script declares the variables anew at each trial, which resets 
them to zero and prevents the counter variables from remembering their 
values. When I declare them as global variables in the userscript, it works 
as intended. I did have to increase the weights from 3 to 6 to compensate 
for the decrease in repeats, but now it does approximate a 1:3 switch ratio.

I will upload the task here soon if you or anyone else want to have a look 
at it. For now I am just glad that it works the way I expected it to work!

On Thursday, April 3, 2014 6:16:29 PM UTC+2, McFarlane, David wrote:
>
> Well, you do well to not take my word for any of this (nor the word 
> of PST staff or documentation) and to test everything for 
> yourself.  So I am glad that I brought this up, and that you tested 
> my statement and reported back.  Looks like my understanding of 
> E-Prime is a little off again. 
>
> I had pretty much assumed that when you run a List (List.Run), it 
> looks at all the settings activated with the last List.Reset, and 
> then runs using those just settings, goodness know what doing a 
> List.Reset during the run would do (terminate the run?  be 
> ignored?).  But I confess I never tested that.  Until I do that, your 
> empirical result trumps my assumption.  Perhaps a List.Rest can 
> construct an Order object for running the List on the fly, in which 
> case doing a List.Reset during the run can affect the rest of the run 
> in a nicely controlled way such as you found.  Might be worth 
> prodding the PST folks and see if they could reveal more about how 
> List.Reset and List.Run really work. 
>
> So if your tests show that everything works to your satisfaction, 
> then you may as well proceed.  And this opens up more possibilities 
> (what happens if you change List.ResetCondition or 
> TerminateCondition, etc., during the run?)... 
>
> Thanks, 
> -- David McFarlane 
>
>
> At 4/2/2014 11:42 AM Wednesday, LaurensK90 wrote: 
> >You mentioned not to use SetWeight while the list is running... but 
> >that's actually exactly what I've been doing. I received a reply 
> >from PST support saying that this was impossible, but after 
> >following your suggestion of adding List.Reset, the switch ratio 
> >works exactly as intended. They also sent me an example design 
> >(attached) using multiple lists with different weights, like you 
> >suggested, but since this is not able to make a trial selection 
> >based on the previous trial, it results in a switch ratio of 1:3.5 
> >instead of 1:3. I know how to solve this, but again, it involves 
> >using SetWeight to set the weight of the inappropriate list to zero 
> >while it's running. 
> > 
> >Does List.Reset have especially disruptive effects on timing, or 
> >does running it on every trial have other negative effects I'm not 
> >aware of? I can see why this method is a bit unorthodox, but since 
> >it works, I feel like I need a very good reason not to use it. 
> > 
> >The cheap solution is probably a good option, but I'd still like to 
> >understand why this is so difficult. 
> > 
> >On Tuesday, April 1, 2014 4:58:48 PM UTC+2, McFarlane, David 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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