202 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



o 



en 



O 



h- 

 < 

 H 

 LU 

 CJ 

 LU 

 > 



D 



0.01 



200 300 



DISTANCE FROM GZ, ft 



400 



Fig. 11 Ratio of ^^^U concentrations in vegetation and soil as a function of distance 

 from GZ at A site, area 11, Nevada Test Site. 



explain the observed variability in the ratios. Most important is the question of 

 proportionality. If vegetation concentration is proportional to soil concentration, lines 1 

 and 2 in Fig. 10 should be parallel. A comparison of their slopes would be a test of that 

 assumption. The slopes for the vegetation and soil concentrations are —0.00898 and 

 -0.023, respectively. In Fig. 10 the two regression lines do not appear to be parallel. 

 Simultaneous 95% confidence intervals for j3i and (^2 , which are rather large because there 

 are so few data points, are given by 



-0.017 <|3i < -0.00098 



-0.032 <|32 < -0.013 



(Morrison, 1967, pp. 107-109). Since the two intervals overlap, one cannot claim that j3i 

 and ^2 differ significantly, although making a judgment on so few observations is risky. 



