alright, I'm probably about to n00b all over myself but, Ive been looking around online and on the excel help database and I'm still having trouble with this, hopefully someone can help.

for a set of numbers I have calculated the mean (1.87mm) and the standard deviation (-0.53mm), now I need to take these numbers and create a normal distribution curve, which will be placed on a graph alongside a graph of the actual distribution curve. I cant figure out how to create the normal distribution curve and I think I've stared at this crap for so long that I'm getting more and more confused.

can anyone help me out with this? it seems like it would be relatively simple, I'm just missing a step somewhere

Thanks in advance

1/21/2007 10:48:05 AM

There isn't a specific Excel function that will spit out a normal distribution for you.

http://support.microsoft.com/kb/213930

This walks you through generating random numbers that you can use to create data points and plot a normal distribution.

1/21/2007 12:10:43 PM

do you have minitab?

1/21/2007 12:16:17 PM

^I dont know what that is, so I'm gonna assume that I don't have it

^^thanks, I tried all of that and got something that I dont believe I am looking for

1/21/2007 1:22:50 PM

Minitab is a statistical analysis tool for data used often in industry. It's the shit.

1/21/2007 2:37:03 PM

i'm gonna assume if someone tells you in a thread on tww about a program you dont have you should get it

1/21/2007 2:39:27 PM

I'm not going to buy a program that performs statistical analysis for the sole purpose of figuring out one problem. I'm sure it would make my life much easier, but I'd never use it again

I figured out how to do it, thanks for the help

1/21/2007 10:45:35 PM

Why is your standard deviation negative? That's mathematically impossible.

1/22/2007 9:41:49 AM

http://www.minitab.com/Downloads/

its free for 30 days

1/22/2007 10:23:06 AM

Why is your standard deviation negative? That's mathematically impossible.

1/22/2007 11:30:58 AM

its mathematically possible, not by definition though. the square root of a number (sq. root is used in calculating stdev) is always possible to be positive and negative, however the definition of stdev is the positive value

1/22/2007 9:57:51 PM

Quote :

"its mathematically possible, not by definition though"

...

1/22/2007 10:04:30 PM

so what'd you end up having to do to get it to work?

1/22/2007 10:40:00 PM

minitab is good, but after I got ahold of xlstat, I'll never go back unless required to do so

http://www.xlstat.com

it's integrated into excel, so no need for all the bullshit of getting stuff into minitab

[Edited on January 23, 2007 at 1:50 AM. Reason : .]

1/23/2007 1:49:57 AM

Quote :

"Why is your standard deviation negative? That's mathematically impossible."

yeah I typed that wrong, it's definetly supposed to be a positive number.

and to get it to work, I created a range of values (x) that encompassed all of the values that gave me the mean and standard deviation, then ran the excel function NORMDIST which created a list of values derived from the first list of x values.

after doing some scaling to make my normal distribution values comparable to my actual distribution curve values, I plotted both curves onto one graph...which was the goal of all this damn work

fun stuff

1/23/2007 9:29:46 PM