RATIOS IN TRANS URANIC ELEMENT STUDIES 207 



Summary 



The appropriate use of ratios in environmental radionuclide research demands some 

 knowledge of the relationship between the two variables composing the ratio. 

 Concentrations and pure ratios are two types of ratios used extensively in environmental 

 transuranic element research. A concentration is the amount of activity per unit of weight 

 or volume, e.g., nanocuries per gram. A pure ratio, say ^^*Pu/^^^Pu or ^^*Pu in 

 vegetation/^ ^^Pu in soil, is used to express a relationship between the two random 

 variables. In either case the ratio is a valid description of that relationship only if the 

 relationship is approximately multiplicative. For concentrations a major problem 

 (addressed in tliis cliapter using two sets of environmental radionuclide data) is 

 determining the aliquot size for which activity is homogeneously dispersed throughout 

 the medium. For pure ratios the problem is assessing whether the relationship is 

 multiplicative. If not, more meaningful methods, such as multivariate statistical 

 techniques, must be found for relating the two variables. This chapter discusses two 

 multivariate techniques, regression and profile analysis, which might be used as a test of 

 the multipUcative assumption. 



Acknowledgment 



This paper was written under U. S. Department of Energy contract EY-76-C -06-1 830. 



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