Excel Wisdom

[mxjames]

Assuming I have two tables, Table 1 and Table 2:

1	9	11		20	40
6	10	23		44	49
10	18	23		24	40
5	10	25		29	44
10	16	18		31	42
1	4	9		43	50

<tbody>
</tbody>

Table 1, are numbers between 1 and 25 randomly selected and
Table 2, are numbers between 20 and 50 randomly selected.
I believe numbers do not lie and therefore there is a sequence between both random outputs. How can excel be used to understand the random sequence and produce more output to the sequence correctly?

 

[pplstuff]

How can excel be used to understand the random sequence and produce more output to the sequence correctly?

Well, I hope you're a mathematician by trade to recognize a closed-form solution for how excel generates its random numbers...
Pseudorandomness - Wikipedia, the free encyclopedia

I'm not sure I understand the second half of the question "and produce more output to the sequence correctly". Do you want to try and forecast the next random number? For a true stochastic process, this cannot be done; but, for a computer there might be a way to determine its method.

 

[shg]

Random numbers do not correlate; you can't use one set to predict another unless they are correlated as a result of a bad algorithm, or deliberately generated as correlated pairs.

VBA's Rnd() function generates a fixed repeating sequence of 2^24-1 numbers (Singles). Excel's RAND() function generates a much longer sequence (~2^44) of Doubles, and unlike Rnd(), cannot be seeded to start with a certain number.

 

[Tom Urtis]

Maybe/Probably it's me, but I don't understand what you are asking exactly. I don't know what you mean by "a sequence between both random outputs" and your expectation to "produce more output to the sequence correctly".

Perhaps this link to Chip Pearson's page on random numbers may help, but if not, some additional explanation would help readers of this page to understand what kind of result you are looking to achieve.

http://www.cpearson.com/excel/RandomNumbers.aspx

 

[Tom Urtis]

More about this:

Random numbers are based on a predictable algorithm. If you know the previous number and the algorithm, you can predict the next number(s) generated by the random function. This sounds counter-intuitive, but that's because random numbers which are generated by computers are not truly random. A computer uses something called a "random number generator" to produce a series of numbers that satisfy what most people would need for randomness, but really, the numbers are not random.

You can test this for yourself. Run this macro on a blank worksheet. It will produce two columns of 1000 rows each of random numbers. In a truly random environment, what would be the odds of any one pair of rows (that is, for example, the value in cell A346 equaling the value of cell B346)? What would be the odds of ALL 1000 equaling each other? You and I would have better luck winning the Powerball lottery jackpot on a day when there's world peace. Run this macro to see just how "random" random numbers are, and are not.

Sub Test1() 
Dim x As Long 
Rnd -1 
Randomize 1 
For x = 1 To 1000 
Cells(x, 1).Value = Rnd 
Next x 
Rnd -1 
Randomize 1 
For x = 1 To 1000 
Cells(x, 2).Value = Rnd 
Next x 
End Sub

 

[shg]

The LCG used by Excel's RAND() function is described at Description of the RAND function in Excel

 

[mxjames]

The numbers are selected randomly from the sets. There is definitely an attitude of selection the computer uses. My question is how do I understand the computers method of selection when to hand I have samples of its output in that random sequence?

 

[mxjames]

Assuming I have two tables,

Table 1 = RAND(1,25) and Table 2=RAND(20,50)

1	9	11		20	40
6	10	23		44	49
10	18	23		24	40
5	10	25		29	44
10	16	18		31	42
1	4	9		43	50

<tbody>
</tbody>

Table 1, are numbers between 1 and 25 randomly selected and
Table 2, are numbers between 20 and 50 randomly selected.
I believe numbers do not lie and therefore there is a sequence between both random outputs.
How can excel be used to understand the random sequence and produce more outputs of the sequence correctly?
HINT=(The numbers are selected randomly from the sets. There is definitely an attitude of selection the computer uses. My question is how do I understand the computers method of selection. The tables are samples of its selection process (row by row))