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.
- Skill level:
Things you need
- Excel 2007
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 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 centre 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.
Tips and warnings
- 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.
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