|  OCT 1993

Letters To S&C by Technical Analysis, Inc.

LETTERS by Technical Analysis, Inc. STANDARD DEVIATION Editor, In the ""Relative volatility index"" sidebar on pages 64-65 of the June 1993 STOCKS & COMMODITIES, the Excel spreadsheet gives the formulas for the up close volatility and down close volatility in columns E and F. Please define for me STDEVP(D2:D11). I would appreciate a numerical answer. Thank you. ROBERT MAAS - Largo, FL The STDEVP(D2:D11) formula in Excel measures the standard deviation of the closing prices listed in cells D2 through D11. Standard deviation measures the variance about the mean. In our case, we are measuring the variance of the last 10 days of closing prices compared with the mean or average of the last 10 days of closing prices. To learn more about standard deviation, I suggest purchasing a used college statistics textbook from your local community college. Or try The Economist Guide to Business Numeracy, a paperback($17.95) just published by John Wiley & Sons, 605 Third Ave., New York, NY 10158-0012, 800-C ALL WILEY. The book covers everything from statistics for business applications to data analysis techniques, chart reading, investment accounting, forecasting and linear programming. —Editor

by Technical Analysis, Inc.