Solved

Statistics Questions

Posted on 2002-07-15
10
297 Views
Last Modified: 2010-05-02
Let's say i had a group of numbers and now i know the mean, median, mode, and range for this group how do i calculate the variance?


Now let's say i want to statistically create a new list based off of the information from the first list.
How would i go about doing that?

Basically what i'm looking for is a way to create a new list with the size of the new list to be specified by the user and once created it will have the same statistical distribution with some randomness and variance built into it.

Easy examples would be nice! :>)
0
Comment
Question by:jrcp
10 Comments
 
LVL 75

Expert Comment

by:Anthony Perkins
ID: 7155658
Please maintain this open question:
FTP Append Method Date: 07/02/2001 09:13AM PST  
http://www.experts-exchange.com/visualbasic/Q_20144619.html

Thanks,
Anthony
0
 
LVL 45

Expert Comment

by:aikimark
ID: 7156150
the variance is the sum of the squares of the (item-avg) differences.
0
 

Author Comment

by:jrcp
ID: 7156995
Okay, so how do you use the variance?
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 18

Expert Comment

by:deighton
ID: 7157006
you can calculate the mean and variance of a list fairly easily, i could come up with code for that.

Making the new list depends on the distribution type you are interested in.
0
 

Author Comment

by:jrcp
ID: 7157014
I would be interested in a normal distribution... If i had some code or info on that I could modify it to change the distribution if i needed to. Just a little rusty on the stats.
0
 

Author Comment

by:jrcp
ID: 7157056
Just to check....

So if my list was

1,2,3,4,5,6
The variance would be
1 + 4 + 9 + 16 + 25 + 36 = 91/6 = 15.1

I guess this seems high since each number is only 1 apart, or it's just because i don't know how you use the variance.
0
 
LVL 45

Accepted Solution

by:
aikimark earned 200 total points
ID: 7157085
You asked me how you could calculate the variance.  What do you mean "How do I use it?"

=======================================
I would try to create your new list similar to the following:
For I=0 to Ubound(itemarray) -2 Step 2
   itemarray(I) = avg + rnd() * (StandardDeviation/N)
   itemarray(I+1) = avg - rnd() * (StandardDeviation/N)
Next

Where StandardDeviation/N is the square root of the variance divided by the number of items in the list.

Note: this assumes that you have an even number of items in your array.  Otherwise, you will have to create a random number = (rnd() * (StandardDeviation/N) * 2) -(StandardDeviation/N)
to be added to each item in the array.
0
 
LVL 45

Expert Comment

by:aikimark
ID: 7157113
If your list were:
1,2,3,4,5,6
The average = (1+2+3+4+5+6)/6 = 21/6 = 3.5

The variance would be
(3.5-1)^2 + (3.5-2)^2 + (3.5-3)^2 + (3.5-4)^2 + (3.5-5)^2 + (3.5-6)^2 = 2.5^2 + 1.5^2 + .5^2 + -.5^2 + -1.5^2 + -2.5^2 = 17.5
0
 

Author Comment

by:jrcp
ID: 7157117
What i meant by "how do i use it" is what is the purpose of variance?  I thought that variance would come into play when trying to create a new list with the same properties. It looks like i'm confused on the difference between std dev and variance.
0
 
LVL 49

Expert Comment

by:DanRollins
ID: 8012496
Hi jrcp,
It appears that you have forgotten this question. I will ask Community Support to close it unless you finalize it within 7 days. I will ask a Community Support Moderator to:

    Accept aikimark's comment(s) as an answer.

jrcp, if you think your question was not answered at all or if you need help, just post a new comment here; Community Support will help you.  DO NOT accept this comment as an answer.

EXPERTS: If you disagree with that recommendation, please post an explanatory comment.
==========
DanRollins -- EE database cleanup volunteer
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Help me. 3 69
Child Form in front 4 56
Problem to line 23 74
Fastest way to find and count same items VB6 16 44
Introduction While answering a recent question (http://www.experts-exchange.com/Q_27402310.html) in the VB classic zone, I wrote some VB code in the (Office) VBA environment, rather than fire up my older PC.  I didn't post completely correct code o…
When trying to find the cause of a problem in VBA or VB6 it's often valuable to know what procedures were executed prior to the error. You can use the Call Stack for that but it is often inadequate because it may show procedures you aren't intereste…
Get people started with the process of using Access VBA to control Outlook using automation, Microsoft Access can control other applications. An example is the ability to programmatically talk to Microsoft Outlook. Using automation, an Access applic…
This lesson covers basic error handling code in Microsoft Excel using VBA. This is the first lesson in a 3-part series that uses code to loop through an Excel spreadsheet in VBA and then fix errors, taking advantage of error handling code. This l…

756 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question