X = m(qH|j)'"Sin 2a|, 



Figure 5, Real test data for example problem 1. Compare 

 the correct fit through the origin with the 

 customary fit. 



**************** EXAMPLE PROBLEM 2*************** 



At least 10 equations relating the velocity of longshore currents to wave 

 characteristics have appeared in the literature. Presumably more will appear 

 as knowledge increases or theory is adapted to specific wave or bathymetric 

 conditions (i.e., specialized for breaker type or bar dimensions). A recent 

 article (Komar, 1979) questions the value of including a measure of beach slope 

 in the general prediction equation and claims better results for 



V = 0.585(gHb)^/2 sin 2ab 

 GIVEN : The same situation and data as in example problem 1. 

 REQUIRED : Determine the best fit version of the type 



V = (gH^) ^''^ sin 2a|3 



and compare the results with those obtained in example problem 1 to see if 

 the beach slope is indeed of any value at this particular site. 



ANALYSIS : For the same reasons stated in example problem 1, regression 

 should require the prediction line to pass through the point (0, 0). 



Let 



Y = V 



X = (gHb)^/2 sin 2ab 

 and regress Y on X using Model II with its extended data set (Fig. 6) 



17 



