ENVIRONMENT AND GROWTH OF THE SOFT CLAM 



291 



T.\Bi.E h-\. — Original and transformed mean, variance, and standard deviation for growth of 18 groups of clams in i-mm. 



classes used in figures B-1 and B-2 



[Transformation is based on formula; Transformed X = log (class midpoint + U. Total number of clams, 1,186) 



7 8 9 10 

 MEAN GROWTH 



II 

 IN 



12 



M M 



13 14 15 



17 18 19 20 21 



Figure B-1. — Standard deviation plotted against arithmetic mean growth for 18 groups of clams listed in table B-1. 

 The slope of the trend line fitted b.v least-squares method indicates the need for transformation to make anal.vsis of 

 variance applicable. 



o 



UJ 



z cr 

 < < 

 cr > 



.2- 



Less t Squares Line 

 E= 0.077— 0.0304 X 



—I 1 1 1 1 1 1- 



.5 .6 .7 .8 .9 1.0 I.I 

 TRANSFORMED MEAN GROWTH 



1.2 



1.3 



1.4 



1.5 



1.6 



Kif:rRE B-2. Variance plotted against aritlinictic mean growth for 18 groups of clams listed in table B-1 after growths 

 were grouped in 2-inni. classes and transformed by taking the log of each class midpoint plus one. The extremely 

 slight slope of the trend line fitted by the least-squares method indicates that this transformation has made variance 



slight slope 



virtually independent of the mean, so analysis of variance method can be used. 



