Re: Statistics [was Re: Dice]
Re: Statistics [was Re: Dice]
- Subject: Re: Statistics [was Re: Dice]
- From: Emmanuel <email@hidden>
- Date: Tue, 26 Oct 2004 21:27:28 +0200
At 2:48 PM -0400 10/26/04, Graff wrote:
On Oct 26, 2004, at 2:28 PM, Graff wrote:
On Oct 26, 2004, at 1:48 PM, Emmanuel wrote:
At 12:46 PM -0400 10/26/04, Graff wrote:
I just ran it 1000 times and got the following distribution:
1 161
2 167
3 173
4 170
5 169
6 160
std deviation = 5.16
So no, it doesn't seem to be perfect but it's probably good
enough for most applications.
Out of curiosity, what would the std deviation be if the random was perfect?
A perfectly even distribution would be for every value to show up
the same number of times. In that case the std deviation would be
0.
<snip>
To calculate standard deviation you first get the mean of your data
set. You then calculate the deviation of each element from the
mean and square it. You sum up these squared deviations and divide
them by the number of items in your data set. Finally you take the
square root of this number.
Since we are an AppleScript list here's a quick handler to calculate
the standard deviation of a list of numbers:
----
on stddev(theSet)
set n to count of theSet
set sum to 0
repeat with val in theSet
set sum to sum + val
end repeat
set mean to sum / n
set sum to 0
repeat with val in theSet
set sum to sum + (val - mean) ^ 2
end repeat
return (sum / (n - 1)) ^ 0.5
end stddev
stddev({161, 167, 173, 170, 169, 160})
--> 5.163977794943
Still quicker:
stdev of (statlist {161, 167, 173, 170, 169, 160})
-- 4.71404520791
(Requires Satimage.osax)
Emmanuel
From Satimage-software, who make Satimage.osax available for free.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Applescript-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden