Random Number Generation Dialog Box

[Bob Harris]

Howdy,

Am using Excel 2001 and want to generate some random numbers from a normal
distribution. A help search tells me about what looks like a wonder dialog
box that will do what I want. But it does not tell me how to get to that
dialog box. I've hunted through menu after menu trying to locate it.
Anyone know where it is?

What's the use of having the function in help if they don't tell you how to
get to it?

Bob H

 

[JE McGimpsey]

Am using Excel 2001 and want to generate some random numbers from a normal
distribution. A help search tells me about what looks like a wonder dialog
box that will do what I want. But it does not tell me how to get to that
dialog box. I've hunted through menu after menu trying to locate it.
Anyone know where it is?

What's the use of having the function in help if they don't tell you how to
get to it?

Well, XL2001's Help, while miles ahead of XL5's and somewhat better than
XL98, was still very much a work in progress. Later versions of XL let
you know that the Random Number Generator Dialog Box is part of the
Analysis Toolpak Add-in (Tools/Add-ins..., check the appropriate
checkbox). Once the ATP is loaded, you can access the RNGDB using
Tools/Data Analysis/Random Number Generation.

Be aware, however, that the ATP's pseudorandom number generator is not
really up to speed statistically. It's probably good enough for casual
use, but for truly serious work, it just plain sucks. XL01's RAND()
function is a bit better, and if you search the Excel archives:

http://groups.google.com/advanced_group_search?q=group:*excel*

you can find posts by David Braden, among others that describe how to
retrieve normally distributed random numbers from RAND(). RAND() is
still not great for XL versions prior to WinXL03 (as patched - the
unpatched version returns negative numbers after a while), including
MacXLv.X. I have high hopes, however, for XL2004, which will be released
shortly.

 

[Bob Harris]

and JE McGimpsey replied:

Well, XL2001's Help, while miles ahead of XL5's and somewhat better than
XL98, was still very much a work in progress. Later versions of XL let
you know that the Random Number Generator Dialog Box is part of the
Analysis Toolpak Add-in (Tools/Add-ins..., check the appropriate
checkbox). Once the ATP is loaded, you can access the RNGDB using
Tools/Data Analysis/Random Number Generation.

Be aware, however, that the ATP's pseudorandom number generator is not
really up to speed statistically. It's probably good enough for casual
use, but for truly serious work, it just plain sucks. XL01's RAND()
function is a bit better, and if you search the Excel archives:

http://groups.google.com/advanced_group_search?q=group:*excel*

you can find posts by David Braden, among others that describe how to
retrieve normally distributed random numbers from RAND(). RAND() is
still not great for XL versions prior to WinXL03 (as patched - the
unpatched version returns negative numbers after a while), including
MacXLv.X. I have high hopes, however, for XL2004, which will be released
shortly.

Thanks, JE, for the very complete answer.

In my case, I was interested in generating some test data for a clustering
program I'm writing for school. I just wanted to create a quick data set
with about 100 samples taken from a mix of 4 guassians in six dimensions.
Unable to to that *quickly*, I just gave up on excel and wrote my own c
program to do it.

So while the "iron is hot" moment has passed, I'll save your message sothat
next time I need to do that I will know how. Thanks again.

"Help" seems to be something that microsoft completely fails to understand.
Every product they make seems to have oodles and oodles of help capability,
but very little of it is of any use. It's just not helpful. For example,
this morning I have had the same experience trying to figure out how to make
histograms. What I find, using the assistant, is that yes indeed there is a
histogram dialog box, and if I could ever find my way to it then that help
would be meaningful. Such help seems to be from the perspective of giving
me some help in understanding how to use something *once I have stumbled
across it*.

From what you say in the message above, I had no hope of finding the random
number generation dialog box anyway, because it's not installed. I spent
about 20 minutes this morning hunting for the histogram dialog box. I'm not
exaggerating the time-- is it a chart function, is it a table fucntion-- the
only way to tell is just to hunt down every menu and dialog path you see.
Now I suspect that it's the same deal-- don't bother looking because it
isn't installed.

Bob H

 

[JE McGimpsey]

"Help" seems to be something that microsoft completely fails to understand.
Every product they make seems to have oodles and oodles of help capability,
but very little of it is of any use.

All I can say is that it's gotten better every version (unlike WinOffice
Help which took a *huge* step backward in Office2003.

From what you say in the message above, I had no hope of finding the random
number generation dialog box anyway, because it's not installed. I spent
about 20 minutes this morning hunting for the histogram dialog box. I'm not
exaggerating the time-- is it a chart function, is it a table fucntion-- the
only way to tell is just to hunt down every menu and dialog path you see.
Now I suspect that it's the same deal-- don't bother looking because it
isn't installed.

Yup - the histogram dialog box is also part of the ATP. In XLv.X there's
a description of how to load the ATP in every (well, every one I've
checked) ATP help topic.