I need to create a Normal Distribution (or Bell) (Gaussian whichever you want to callit) for class.

Hi Taneria,

Here's an example:

The legs are more extended than the usual Bell curve, as the data range for the scores is ±6 standard deviations from the mean. Below is an example with the data range reduced to ±4 standard deviations from the mean.

Formulas:

Rows 1 and 2 are Header Rows. A2 contains the Standard Deviation value (2.5), B2 contains the label "Score", used on the chart, and C2 contains the Mean value (70).

A3 and filled down: =(ROW()-15)/2

B3 and filled down: =$C$2+$A$2*(ROW()-15)/2

OR

B3 and filled down: =$C$2+$A$2/*A3

The formula in column A calculates the number of standard deviations from the mean that will be used in each row. As written, the Mean value will be in row 15, and the increment in value will be 1/2 a standard deviation for each row away from row 15.

The formulas for column B calculate the score that is the distance from the mean indicated in column A.

The first version does the calculation independently of the value in column A.

The second version uses the value calculated in column A, making editing simpler if more or fewer data points are wanted for the graph.

C3 and filled down: =NORMDIST(B,$C$2,$A$2,FALSE)

This calculates the Probability Density for each score, the Y value in the graph.

The second graph is created by selecting the cells shown in the second image, then choosing the Scatter Chart from the menu in the Chart button. The first is done the same way, selecting more rows of the table before choosing the type of chart.

Regards,

Barry

Taneria,

The Mac comes with a little, but powerful, app called Grapher that was really made for such requests.

You enter the expression, Grapher makes the curve. Here's an example using your case:

All the programming and data it took was to write the expression that you see above. I copied it in an enlarged form to make the expression easier to read.

Jerry