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Topic: Is there a name for this distribution?
Replies: 6   Last Post: May 27, 2014 11:17 AM

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Richard Ulrich

Posts: 2,866
Registered: 12/13/04
Re: Is there a name for this distribution?
Posted: Nov 16, 2013 6:48 PM
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On Sat, 16 Nov 2013 14:34:56 -0800 (PST), Steve
<petertwocakes@googlemail.com> wrote:

>I want to program a random distribution in the range 0.0 to 1.0, similar to a normal distribution, but with the centre point shifted to, say, 0.25.
>The quality of the randomness isn't crucial, as long as it is shifted.
>Given that I can create a random normal-ish distribution, which is good enough for my purposes, by averaging a few regular Random(0,1), is there a technique to make a shifted version?
>


Problem number 1: "similar to normal" is not at all
specific enough, especially when you want to assign
a small range. Normal has infinite extent to both
sides.

If you just want a standard normal with a new location
and variance, you could start with standard normal,
mean=0.0 and variance= 1.

Then multiple by a number to limit the range; and
add a constant to adjust the mean.

If you wanted to confine a normal to [0,1] while
preserving the first 3 SD of range, you would take
a normal deviate and divide by 9, then add 0.5.
Trim or truncate (whichever you arbitrarily decide)
whatever draws exceed the range.

If you want a skewed distribution between 0 and1,
you might look at the beta.

--
Rich Ulrich



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