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Excel Tutorial: Descriptive Statistics Functions In Microsoft Excel, open the Experiment Excel worksheet file. The FocalLength sheet contains the recorded data from an experiment to measure the focal length of a lens. The lens is placed at a specified distance from the arrow painted on the light bulb (object distance). The screen is moved until a sharp image of the arrow appears on the screen. The distance between the lens and the screen is the image distance. The experiment is repeated 30 times using a different object distance each time. The distances are measured in “cm” (centimeters).

Page 1 Cell E35: Calculate the mean (or average) focal length – rounded to the nearest hundredth. The range of values is E5:E34 or FocalLength. Because the formula is not being copied, either range identifier can be used. The mean calculation is either =AVERAGE(E5:E34) or =AVERAGE(FocalLength). The next step is to round off the calculation to the nearest hundredth (2 decimal places). =ROUND(AVERAGE(E5:E34),2) or =ROUND(AVERAGE(FocalLength),2) Cell E36: Calculate the count. =COUNT(E5:E34) or =COUNT(FocalLength) Cell E37: Calculate the sample standard deviation for the focal length data. =STDEV(E5:E34) or =STDEV(FocalLength)

Cell E5: For the first trial, calculate the focal length of the lens (rounded to the nearest hundredth). The formula to calculate the focal length is F = O*I / (O+I) where O is the object distance I is the image distance On row 5, what cell contains, O, the object distance? On row 5, what cell contains, I, the image distance? Write the Excel formula to calculate the focal length. The first value is 29.89. (The actual formula is listed on the last page.) Copy the formula in cell E5 down through E34.

Name the range: Select the cells E5:E34. Name this range FocalLength. (Remember, you cannot put a space in a cell or range name.)

Cell E39: Calculate the absolute error, which is the absolute value of the difference between the experimental mean (average focal length) and the accepted focal length. =ABS(E35-E38) Cell E40: Calculate the confidence interval for the focal length distribution. In this experiment, alpha is 0.05 (cell B40). The syntax of the function is CONFIDENCE(alpha, StandardDeviation, Count) The value is rounded to the nearest hundredth. Complete the formula by filling in the value or cell address. The actual formula is listed on the last page. =ROUND(CONFIDENCE( ____ , ____ , ____) , ___ ) Cell E41: Calculate the highest (or maximum) focal length measured in the experiment. =MAX(E5:E34) or =MAX(FocalLength) Cell E42: Calculate the lowest (or minimum) focal length measured in the experiment. =MIN(E5:E34) or =MIN(FocalLength)

Excel Tutorial: Descriptive Statistics Functions Format the table:

Page 2 Select the data in columns C and D

Hide rows 36-37. Right-Click on the “36” on row 36. Select Hide Row. Repeat the process for row 37.

Draw a thick border around the table. Draw thin borders inside the table to separate the different sections of the table. The title above the table is already centered above the table.

Click on the Number button on the Home ribbon. Select the category: Custom. Create a new type 0.0 “cm”. The 0.0 indicates a number showing 1 decimal place. The “cm” must be inside quotes because some letters, including the “m” are format commands.

The contents in the cells on row 4 is not fitting within each cell. Select cells B4:E4

Format the alignment of the selected cells. Select the option, Wrap Text.

The top of the table should look like the following.

Repeat the process with the values in column E. In this column use the custom format, 0.00 “cm”. The values in this column have been rounded to the nearest hundredth – 2 decimal places. Save. ______________________________________________________________

Excel Tutorial: Descriptive Statistics Functions Switch to the Height worksheet. Twenty males and twenty females were randomly selected from customers walking the local mall. The height of each selected person was measured (in inches) and recorded. The data is shown in the table. At the bottom of the table, calculate the mean height (average), the maximum height, the minimum height, and the sample standard deviation of the height data for each group (Male/Female). Round off the mean and standard deviation calculations to the nearest tenth (1 decimal place). For each calculation, write the formula in column C and copy across to column D. Because the formulas are being copied, you cannot use range names, but use the actual range, C5:C24. If you have problems writing the formulas, the actual formulas are on the last page. The values for these formulas are:

Format the data and calculations in columns C and D using the custom format, 0.0 “in”. Follow the steps shows in the previous problem.

Page 3 On the Descriptive Statistics page, click on the the input range.

(select range) button to define

Select the column header and the focal length values for the 30 trials.

Check “Labels in first row” Check “New Worksheet Ply” named Statistics Check “Summary statistics” Check “Confidence Level for Mean at 95% (or alpha of 0.05) Click OK

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Descriptive Statistics Tools: Return to the FocalLength worksheet. Microsoft Excel has several built-in statistical tools to assist users in doing statistical analysis without having a knowledge of the statistical functions.

On the

ribbon, click on Format the cells and columns as shown on the next page.

Select Descriptive Statistics from the list of Analysis Tools.

Excel Tutorial: Descriptive Statistics Functions

Page 4 Formulas: FocalLength worksheet Cell E5:

=ROUND(C5*D5/(C5+D5),2)

Cell E40:

=ROUND(CONFIDENCE(B40,E37,E36),2)

Height worksheet Cell C25

=ROUND(AVERAGE(C5:C24),1)

Cell C26

=MAX(C5:C24)

Cell C27

=MIN(C5:C24)

Cell C28

=ROUND(STDEV(C5:C24),1)