Beefy Boxes and Bandwidth Generously Provided by pair Networks
good chemistry is complicated,
and a little bit messy -LW
 
PerlMonks  

Re: Statistical data analysis

by Anonymous Monk
on Jun 05, 2002 at 17:31 UTC ( #171926=note: print w/ replies, xml ) Need Help??


in reply to Statistical data analysis

Your method of calculating variance can result in loss of significant digits. For example, the following data produces a variance of 0 for X on my machine (causing div-by-zero errors later). The variance should be the same for both X and Y (as the data differs only by a constant).

999999997	9999997
999999998	9999998
999999999	9999999

Better results may be achieved by "centering" your variance calculation about the mean.

my $VX = 0; $VX += ($_ - $MX)**2 for @x; $VX /= $Xn;

You are also making far more passes over the data than necessary.


Comment on Re: Statistical data analysis
Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://171926]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others lurking in the Monastery: (5)
As of 2014-12-28 10:29 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    Is guessing a good strategy for surviving in the IT business?





    Results (180 votes), past polls