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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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 petertwocakes@googlemail.com Posts: 27 Registered: 1/8/09
Re: Is there a name for this distribution?
Posted: Nov 17, 2013 2:10 PM
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On Saturday, November 16, 2013 11:48:03 PM UTC, Rich Ulrich wrote:
> On Sat, 16 Nov 2013 14:34:56 -0800 (PST), Steve
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> >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.
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> >The quality of the randomness isn't crucial, as long as it is shifted.
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> >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?
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> >
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> Problem number 1: "similar to normal" is not at all
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> specific enough, especially when you want to assign
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> a small range. Normal has infinite extent to both
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> sides.
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> If you just want a standard normal with a new location
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> and variance, you could start with standard normal,
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> mean=0.0 and variance= 1.
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> Then multiple by a number to limit the range; and
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> add a constant to adjust the mean.
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> If you wanted to confine a normal to [0,1] while
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> preserving the first 3 SD of range, you would take
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> a normal deviate and divide by 9, then add 0.5.
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> Trim or truncate (whichever you arbitrarily decide)
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> whatever draws exceed the range.
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> If you want a skewed distribution between 0 and1,
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> you might look at the beta.
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> --
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> Rich Ulrich

Thanks Rich. I don't understand 100% at the moment but there's enough there now that at least I know what to search for, study, and try. Specifically, I don't know what 'normal deviate' means. If it means the rate of change of the normal curve, I don't know how to calculate that.

Date Subject Author
11/16/13 petertwocakes@googlemail.com
11/16/13 Richard Ulrich
11/17/13 petertwocakes@googlemail.com
11/17/13 Richard Ulrich
11/25/13 Jeff Miller
11/26/13 mathman1
5/27/14 godspeed.wang@gmail.com

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