variables X2 and Xh are dominant throughout all of the combinations, and 

 variable XI through all but one combination. Variable X6, wind velocity 

 onshore,, takes the place occupied by XIO in the five Xs at a time combina- 

 tion of table 3. Angle of wave approach, XIO, then appears in the com- 

 bination of six Xs at a time. Thus, wind velocity again appears important 

 in influencing lonshore-current velocity. 



Table 5. -The Strongest Percent Reductions in Longshore Current Velocity 



Sum, of Squares Attributable to Combinations of Eleven Independent 

 Variables (X3 and X5 Removed From The Original Thirteen Xs). 



Percent 

 Independent Variable Combinations Redcution in SS 



Ul.lO 

 ^7.23 

 51.98 

 57.10 

 10 59-77 



10 62.0k 



Table 6 summarizes the combinations of independent variables that 

 least influence V. The table reveals certain variables that contribute to 

 both the weakest and to the strongest combinations. It is instructive to 

 refer to the weakest (table 6) and the strongest (table 2) combinations of 

 independent variables taken six at a time. Intuitively, we might expect 

 that none of the six variables that appear in the strongest combination 

 (Xs 1, 2, 3, 5, 1, 10) would appear in the weakest combination (Xs 8, 9^ 

 10, 11, 12, 13). It is found, however, that XIO does appear in both com- 

 binations. 



When the number of variables is fairly large, as in this study, it 

 is not unusual to find that as the number of Xs per combination is increased, 

 a variable whose net contribution is of the order of 1 or 2 ^, may "rise 

 to the top" when combined with a very strong combination of Xs, whereas 

 when combined with very weak Xs, its own slight contribution is not suffi- 

 cient to raise the total contribution by any significant amount. 



25 



Two Xs 

 at a time 





2 



h 







Three Xs 

 at a time 



1 



2 



h 







Four Xs 

 at a time 



1 



2 



k 





7 



Five Xs 

 at a time 



1 



2 



k 



6 



7 



Six Xs 

 at a time 



1 



2 



k 



6 



7 



Seven Xs 

 at a time 



1 



2 



k 



6 



7 



