Problem in randomization

[Ice Tsui]

I have found problem in getting the order of the sequence.  I have used to
function "Order.Advance" so as to generate a list of random ordered trials,
however, I can't get the way the view the order of the trials from Eprime,
could you give me some suggestions in doing so?
Thank you very much.

It seems to be that doing the randomization in Excel is more simple...
It does not make great different, too.  Is it right?

Best Regards,
Ice


>===== Original Message From "Tony Zuccolotto" <anthony.zuccolotto at pstnet.com>
=====
>Ice,
>
>There is really no automatic way to tweak the randomization into a form
>which you like.
>
>You could limit the chance of runs by changing the weight on the
>individual cell types and increasing the number of cycles accordingly
>until you get 100, e.g.
>



>Assuming you have 1 Cycle of 100 Samples (=100 samples) defined as
>Weight	Condition
>25		red
>25		blue
>25		green
>25		yellow
>
>You could redefine this as 5 Cycles of 20 Samples (=100 Samples) defined
>as
>Weight	Condition
>5		red
>5		blue
>5		green
>5		yellow
>
>This would theoretically reduce the maximum run of a single condition to
>5 (but in practice it is likely to be even less than that).  Note there
>is an exception at the re-shuffle points, e.g. if you had 2 blue trials
>as trials 19 & 20 then the list was reshuffled for the next cycle you
>could start out with blue trials again...
>
>Another way to set this up is to allow E-Prime to do an initial
>shuffling for you and then in the trial proc just save the exemplars in
>an array (rather than presenting them to the subject).  Then you write
>script logic to cycle through the array and swap individual locations in
>the array as needed (because you are just swapping you can easily assure
>that the Ns remain balanced in each condition).
>
>Once you have an array with a "valid" randomization then you can either
>build a string to pass to an ExplicitOrder object and set a List to use
>the ExplicitOrder (see the E-Basic Help for an example), OR you could
>dynamically write out a tab-delimited file of the entire set of trials
>and have another List read in the exemplars at run-time and just run
>them in sequential order.
>
>If you want to take more trial by trial control of exemplar
>sampling/filtering you can write script to save just the last N
>conditions sampled in a global array/queue.  At the beginning of each
>trial you use script to compare the current condition with those past.
>If the condition is not valid (under whatever logic you decide to use)
>then you just call "Exit Sub" in script.   For example to test for and
>eliminate a single repeat...
>
>	If c.GetAttrib("Condition") = g_strLastCondition Then
>		Exit Sub
>	Else
>	   g_strLastCondition = c.GetAttrib("Condition")
>	End IF
>
>The Exit Sub call causes the current Procedure to return with no logging
>occurring (e.g. you essentially skip the trial).
>
>If you choose this algorithm then you must also set the number of cycles
>on your list to a value higher than you would normally use (because you
>are throwing away exemplars).   Because of this you also have to track
>the number of trials yourself and cause the List to terminate when the
>maximum number of trials is hit by calling ListName.Terminate.   The
>other caveat of doing this is that you now also assume responsibility
>for making sure you have a balanced N in each of your conditions, i.e.
>E-Prime will just keep presenting trials, if you throw them away it
>can't guarantee to get equal Ns in all conditions.
>
>Hope that gives you some ideas.
>Tony
>
>*** DISCLAIMER: VIEWS EXPRESSED ARE MY OWN AND DO NOT NECESSARILY
>REFLECT THOSE OF MY EMPLOYER ***
>Anthony P. Zuccolotto
>Vice President of Operations
>Psychology Software Tools, Inc.
>2050 Ardmore Boulevard
>Suite 200
>Pittsburgh, PA 15221-4610
>Phone     412-271-5040
>FAX       412-271-7077
>Email     anthony.zuccolotto at pstnet.com
>Internet  http://www.pstnet.com/
>
>
>
>> -----Original Message-----
>> From: Ice Tsui [mailto:icetsui at graduate.hku.hk]
>> Sent: Friday, April 19, 2002 4:00 AM
>> To: eprime at mail.talkbank.org
>> Subject: Problem in randomization
>>
>>
>> Hello,
>>
>> I am a new user of the Eprime.  I have one question to ask about the
>> randomization in Eprime.  In my experiment, there are totally
>> 4 different
>> kinds of trials, combining together to form a block with 100
>> trials with each
>> kind of trials appear for 25 times.
>>
>> I found that the randomized events sometimes repeat one kind
>> of trials too
>> frequently.  Is there any way to reduce the number of times
>> that one kind of
>> trial repeats sequentially?
>>
>> Thank you very much!!
>>
>> Best,
>> Ice
>>
>> ______________________________________________________________________
>> Tsui Sum Yin Ice
>> Mobile: 93221306
>> Email: icetsui at graduate.hku.hk
>> ______________________________________________________________________
>>
>>
>>

______________________________________________________________________
Tsui Sum Yin Ice
Mobile: 93221306
Email: icetsui at graduate.hku.hk
______________________________________________________________________