CONTENTS 



Page 



CONVERSION FACTORS, U.S. CUSTOMARY TO METRIC (SI) 5 



SYMBOLS AND DEFINITIONS 6 



I INTRODUCTION TO REGRESSION 9 



II A PROBLEM WITH THE CUSTOMARY APPROACH 11 



III SOLUTION TO THE PROBLEM 12 



1. Regression Through the Origin 12 



2. Regression Through Any Arbitrary Point (a, b) 12 



IV SELECTING BETWEEN MODELS I AND II 13 



V EXAMPLES 15 



LITERATURE CITED 20 



TABLES 



1 Adjustment of standard elements produced by programs using 



extended data 1^ 



2 Field calibration data , 16 



3 Extended data set No. 1 19 



4 Extended data set No. 2 19 



FIGURES 



1 Application of Model I produces an intercept (a) , which may be a 



useful estimate of a component of longshore flow which is independ- 

 ent of wave conditions and presumably pervades the entire data set. . 10 



2 Application of Model I identified a threshold value below which 



waves cause no damage 10 



3 Application of Model II forces a zero- intercept solution H 



4 Model II estimates an increase in Y per unit increase in X that 



is nearly twice that predicted using Model I H 



5 Real test data for example problem 1 .... 17 



6 Real test data for example problem 2 and fitted equations 18 



