STDEV example

Note for this example that covar(X, Y) represents the covariance of (X, Y), stdev(X) is the standard deviation of the X data, and stdev(T) is the standard deviation of the Y data. For the MathCad program ( 1986-2001 MathSoft Engineering Education, Inc., 101 Main Street Cambridge, MA 02142-1521), the sldcvfW) is represented by the variable symbol Sr, which can be thought of as the set of many possible standard deviations for a set of data X. 

Many worksheet functions can be used in a 3-D formula, for example AND, AVEDEV, AVERAGE, COUNT, COUNTA, DEVSQ, LARGE, MAX, MEDIAN, MIN, OR, PRODUCT, SMALL, STDEV, SUMSQ, VAR. 

To solve this example you first need the mean and standard deviation. Use the Excel commands =AVE RAGE (range) and =STDEV(ranpe) which give 7.14 and 3.96 for the mean and standard deviation, respectively. 

Excel has built-in functions for average and standard deviation. Enter the numbers 7, 18, 10, and 15 in cells A1 through A4 of a spreadsheet. In cell A5, enter the formula =AVER AGE( A1 A4) and in cel 1A6, enter the formula =STDEV( A1 A4) . Results in the spreadsheet in the margin reproduce those in the example above. For a list of built-in functions, go to the Formulas ribbon and select Insert Function. In the window that appears, you can browse categories of functions or all functions. 

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