I think if all you are interested in is a random set of numbers then the difference with the three approaches is when 'randomness' is introduced. In the first case the set is randomized before numbers are accessed sequentially. In the second case 'randomness' is introduced when one is picking a number at random from a sequential list. In the third case the numbers in the set are randomized and then one is picked at random; so two levels of 'randomness'. Either way random is random so it doesn't make a difference ergo Conrad's analogy holds true.
 
"Excellent people exceed expectations".


From: Rad! <conradakunga@gmail.com>
To: Skunkworks Forum <skunkworks@lists.my.co.ke>
Sent: Fri, January 22, 2010 4:04:59 PM
Subject: Re: [Skunkworks] random sampling

It should be pretty straightforward to prove using probability.

But before we get there let's use a different analogy.

Say you have a pack of cards. If you shuffle the pack thoroughly and then pick out cards at random, the randomness of the picked cards is just as random as if you shuffled the pack twice before picking the cards.

Shuffling already random cards again does not introduce, for lack of a better word, 'more randomness'

Ergo given a randomized set

[1,5,2,4,3]

So for a single run If you pop the elements in sequence, the result will be as random as popping them at random.

On Fri, Jan 22, 2010 at 3:51 PM, wesley kirinya <kiriinya2000@yahoo.com> wrote:
I've noticed a difference between accessing a sorted set randomly versus accessing a randomized set randomly. I've not checked accessing a sorted set randomly versus accessing a randomized set sequentially.

NB: I always re-seed the random number generator with unique values (i.e. I dont repeat the seed value) before each random call.

A sound math/statistical explanation would be 8~)


 


--- On Fri, 1/22/10, Rad! <conradakunga@gmail.com> wrote:

From: Rad! <conradakunga@gmail.com>
Subject: Re: [Skunkworks] random sampling
To: "Skunkworks Forum" <skunkworks@lists.my.co.ke>
Date: Friday, January 22, 2010, 1:23 PM


I actually doubt there is any difference in any of the three scenarios.

A - [1,2,3,4,5]

B - [5,1,4,2,3]

Given one pass to access each set, accessing set A randomly for values should give you results just as random as accessing set B regardless if randomly or in sequence

On Fri, Jan 22, 2010 at 2:15 PM, Nicholas Loki <lokimwenga@yahoo.com> wrote:
Hi Wesley/ Rad,
 How about this:


>> Or, for that matter, a randomized set sequentially

You get a sequential set of random values.

>> sorted set randomly

You get a random value set with a high likelihood of some sortedness :-).

>> randomized set randomly?

Everything is random.

Caveat: No scientific basis to my observations :-).

KR,
Loki
 
"Excellent people exceed expectations".

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