Y = dependent variable 



a = Y intercept at x = 



b = slope of the line 



X = independent variable 



The calculation in linear regression is for b and for a. 



This analysis in growth was used because it is the best way to 

 establish fits for scatter diagrams which relate growth increment to 

 initial size. 



The formulas used to establish the equation are: 



Zxy-il2i(^ 

 b =— 3 



Zx' 



Y - b X 



yx 



where Y and X are the means of the respective variables. 



Tests of significance in regression involve testing b values to see 

 if they are different from or any other b value. These tests are 

 best accomplished with t tests by: 



(b -0) 



t = -iL*"" 



h 



where S, = standard error of the regression coefficient. 



A t value greater than the tabled t value at the appropriate level 

 of probability is evidence of a significant difference. 



65 



