A normal distribution curve, sometimes called a bell curve, is a way of representing a spread of data in statistics. Normal distributions are bell shaped (that's why they are sometimes called bell curves), and have a symmetrical distribution with one single peak. Computing normal distribution curves is a time consuming process by hand. However, with Excel 2007, you can make an Excel chart of the normal distribution in minutes.
To graph any other normal distribution (other than a standard normal distribution), change the mean and standard deviation values in =NORMDIST(a1,0,1,0). The second digit represents the mean and the third digit the standard deviation.
Enter -4 in cell A1. Enter -3.75 in cell A2. Highlight both cells and grab the fill handle (the tiny box in the bottom right hand corner) with your mouse. Drag the fill handle to cell A33 and release the mouse.
Enter =NORMDIST(a1,0,1,0) into cell B1. This tells Excel to calculate the standard normal distribution from the value you entered in cell A1 with a mean of 0 and a standard deviation of 1. Press enter.
Using the same motion you used in Step 1, drag the fill handle from the corner of cell B1 down to cell B33.
Highlight cells A1 through A33 by holding the the left mouse button down and dragging the cursor.
Select "Insert" from the toolbar, then "Scatter," and "Smooth Line Chart."
From Chart Tools at the right hand side of the toolbar, select "Layout," "Axes," "Primary Vertical Axis," then "None". This step will make the y-axis disappear.
Select "Axes" from the center toolbar, then "Primary Horizontal Axis". Select the bottom option ("More Options"). Change the minimum x-value to -4 and the maximum x-value to 4 by pressing the appropriate radio button and filling in the values.
- To graph any other normal distribution (other than a standard normal distribution), change the mean and standard deviation values in =NORMDIST(a1,0,1,0). The second digit represents the mean and the third digit the standard deviation.
About the Author
Stephanie Ellen teaches mathematics and statistics at the university and college level. She coauthored a statistics textbook published by Houghton-Mifflin. She has been writing professionally since 2008. Ellen holds a Bachelor of Science in health science from State University New York, a master's degree in math education from Jacksonville University and a Master of Arts in creative writing from National University.