How random is random?

[David McFarlane]

Tobias,

You have asked a very deep and excellent question of a sort that no 
doubt has lead to several dissertations, so I will not answer it in a 
short online post.  I will say that E-Prime just uses the standard 
pseudorandom number generator provided in Microsoft Visual Basic for 
Applications.  (And AFAIK Excel uses the same PRNG (after all it relies 
on VBA, just like E-Prime), so the method used by Vasiliqu.ee should 
produce the same results as E-Prime.)

To really approach this question, we must first understand what we mean 
by "random", then go on to study "random number generation" and 
"pseudorandom number generator".  For an introduction you should look up 
these topics on Wikipedia.  (While you are at it you might also look up 
"shuffling" and "Fisher–Yates shuffle", since we most often use E-Prime 
randomization to shuffle a List.)  Then you could ask more pointed 
questions about randomization in E-Prime.

Regards,
-- David McFarlane, Professional Faultfinder
"When all is said and told, the 'naturalness' with which we use our 
native tongues boils down to the ease with which we can use them for 
making statements the nonsense of which is not obvious."  Edsger W. 
Dijkstra, "On the foolishness of 'natural language programming'" 
(www.cs.utexas.edu/users/EWD/transcriptions/EWD06xx/EWD667.html ).

Siatra Vasiliki wrote:
> Well, when I want to use a randomized exp I prefer a more
> unsophisticated way.
> I use the RAND function in excel for my items (and this can be done
> also within subcategories)
> and then have the sequential choice for the selection order.
> But in this way you have the same random order for every subj.
> 
> Vasiliqu.ee
> 
> On Feb 11, 11:00 am, Tobias <tobias... at gmail.com> wrote:
>> Hi together,
>>
>> I was wondering: What's your experience with E-Prime randomizing
>> things? It sometimes occured to me that e.g. conditions from a list
>> are not that randomly picked.
>> Just yesterday I used some InLineScript "y = random(1,180) in order to
>> pick a bitmap. As these bitmaps content a line of a certain angle and
>> are put on the screen in a matrix, you can kind of see how "mixed up"
>> it looks. It seems to me that which number is picked relies to some
>> extent on the number picked before. No real random...
>>
>> Do you know if there is any way to draw random numbers in a better
>> way? To optimise the random seed?
>>
>> Thanks a lot,
>> Tobias

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