9 Replies Latest reply on Feb 12, 2010 8:08 PM by akilleen

# How to draw a Normal (bell-shaped) distribution curve?

I did a search for this and nothing came up, so apologies if it's been asked before.

How does one draw the bell-shaped or Normal distribution curve used that's widely in statistics?

Tony

• ###### 1. Re: How to draw a Normal (bell-shaped) distribution curve?

and it needs to be mathematically accurate?

-JM

• ###### 2. Re: How to draw a Normal (bell-shaped) distribution curve?

No, it doesn't need to be mathematically dead-on accurate. Just a vector graphic that looks like a bell curve for teaching purposes.

Tony

• ###### 3. Re: How to draw a Normal (bell-shaped) distribution curve?

I would just draw half of it with the pen tool and mirror for the other half, so it is perfectly symmetrical. Then you could join (smooth) the two topmost points to form the apex. See my attached example.

-JM

• ###### 4. Re: How to draw a Normal (bell-shaped) distribution curve?

You can use mine and adjust the curve to your liking if you want to.

-JM

• ###### 5. Re: How to draw a Normal (bell-shaped) distribution curve?

Three curve points with the pen tool should do it. To draw a curve point, click-and-drag then release. Repeat and the next point will be joined to the first. Repeat again for the third point.

• ###### 6. Re: How to draw a Normal (bell-shaped) distribution curve?

Thanks very much for all the help. This is just what I needed!

• ###### 7. Re: How to draw a Normal (bell-shaped) distribution curve?
for teaching purposes

Tony,

Just FYI: Deneba Canvas (a drawing program in the same category as Illustrator) has a feature for generating curves by formulae.

JET

• ###### 8. Re: How to draw a Normal (bell-shaped) distribution curve?

And, Tony, as implied by the answer James gave, and depending on the teaching purposes, no offence intended, if you wish a close resemblance it is more easily obtained with an actual curve to trace with the Pen Tool; in different cases, the triple ClickDragging is especially suited for an asymmetric shape, whereas a double ClickDragging followed by a reflexion is especially suited for a symmetric shape.

• ###### 9. Re: How to draw a Normal (bell-shaped) distribution curve?

Thanks again, everyone for the help! I've got it now.