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# Statistics: Standard Error and Sampling Size

Mr. James McWhinney, president of Daniel-James Financial Services, believes there is a relationship between the number of client contacts and the dollar amount of sales. To document this assertion, Mr. McWhinney gathered the following sample information. The X column indicates the number of client contacts last month, and the Y column shows the value of sales (\$ thousands) last month for each client sampled.

a. Determine the regression equation.
b. Determine the estimated sales if 40 contacts are made.

Number of contacts: X
14, 12, 20, 16, 46

Sales(\$thousands): Y
24, 14, 28, 30, 80

Number of contacts: X
23, 48, 50, 55, 50

Sales (Thousands): Y
30, 90, 85, 120, 110

Questions:
a. Determine the standard error of estimate.
b. Suppose a large sample is selected (instead of just 10). About 95 percent of the predictions regarding sales would occur between what two values?

#### Solution Summary

This solution calculates the regression equation, estimated sales, standard error of estimate, and 95% of predictions regarding sales in a stepwise explanation. All formulas used are included.

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