HOW TO USE THE COMPUTER TO ANALYZE TEST DATA.

The wide availability of desk computers, time-shared computer terminals, graphical CRTs (cathode-ray tubes) and plotters enables engineers now to analyze their own data by interacting with these computer devices. Most computer installations include regression programs. While it is desirable to know the details of the calculations that the computer does, all that one really need know are the assumptions being made. The discussion of the subject is presented under headings - residual analysis; regression analysis by residuals; first phase of regression analysis; second phase of analysis; residual plot for model of equation (2); residual plot for model of equation (3); third phase analysis; residual plot for model of equation (g); comparison of the two models; goodness-of-fit; check for data deficiencies. It is shown by an example that more than one good-fitting model may exist, and the choice of the proper model should be made from both engineering and statistical considerations.