We can execute a norm.dist. in excel by using the mean and standard deviation of a given data set. This tutorial will teach us how to calculate normal distribution in excel.
Figure 1: Normal Distribution
How to Use the Excel norm.dist
- We will create a table of data
Figure 2: Table of data
- We will click on Cell C14 to calculate the mean of our data. We will type this formula =AVERAGE(C4:C13) into the cell to automatically calculate the average.
Figure 3: Formula for Average
- This will give us the average value of our data
Figure 4: Average or Mean value of our data
- We will now calculate the standard deviation of our data set by typing this formula
=STDEV(C4:C13)into Cell C15
Figure 5: Standard deviation formula
- This will give us the answer to our standard deviation
Figure 6: Standard deviation
- We will now determine the normal distribution of our data set by using clicking on Cell D4. We can use this formula
=NORM.DIST(C4,C14,C15,FALSE). We can also follow this procedure by selecting the fx function above the worksheet, this will open a dialogue box
Figure 7: Dialogue box for fx
- We will type normal distribution in the search option, we will now select norm.dist. This will bring out a dialog box, requesting for X, Mean, Standard deviation and cumulative.
Figure 8: Normal distribution dialog box
- We will now input the information; where X is score of the student in cell C4, we will click on cell C4, then we will click on cell C14 to input the mean, then we will click on cell C15 to input the Standard deviation. We will now type TRUE if we want the cumulative distribution function or FALSE in the cumulative box if we want the probability density function.
TRUE means the probability that the student scored exactly the score in Column C or less than the score in Column C
FALSE means the probability that the student scored exactly the score in Column C
Figure 9: Normal Distribution
- This will return the result
Figure 10: Normal Distribution
- We can repeat the same procedure for the remaining data set
Figure 11: Normal distribution
How to Use the Norm.s.dist Function
Norm.S.Dist is different from the Norm.Dist function. Norm.S.Dist is used to convert Z values to expected probabilities of a particular occurrence in a data set. Z is the standard deviation distance from the original mean value.
- To perform Norm.S.Dist, we will create an additional column for the standardized value and the Norm.S.dist results
Figure 12: Columns for Standardized Value and Norm.S.Dist
- To calculate the standardized value (Z) for Cell E4, we will click on the fx operation and type into the search box STANDARDIZE, then we will select the standardize option, which will open a dialog box. This will request for the X, mean and standard deviation values.
Figure 13: Dialog box for Standardize value
- We will now input the data requested to calculate the standardized value for Cell E4
Figure 14: Values for calculating Z
- This will return the result in Cell E4
Figure 15: Standardized value
- We will input the value of Z, then we will type TRUE if we want the cumulative distribution function or FALSE in the cumulative box if we want the probability density function.
Figure 16: Inputting the data for Norm.S.Dist
- We will now click OK to display the result in Cell F4
Figure 17: Result for Norm.S.Dist
- We can repeat this operation for the remaining data
Figure 18: Norm.S.dist