FIELDS W, X. and Y 



Columns 68; 69 and 



70; and 71 



B. Intensity of response of the individual organism considered as a VARIABLE OF DIFFERENT 

 IN DIVIDUALS; INCIDENCE of a given intensity of individual response IN A GROUP OF 

 INDIVIDUALS; the expression "intensity of response" when applied to a group of individuals , 

 is the DEGREE OF INCIDENCE of specified intensity of individual response . 



In addition to measuring intensity of response in an individual organism (section A above), 

 a third factor is often introduced, that of variation in individuals. By fixing this intensity 

 of response in the individual organisms as a point of reference, a number of individuals can 

 be tested to determine the percentage of individuals that will respond at that given intensity 

 of individual response at any given quantity of test compound. Commonly, the intensity of 

 individual response is fixed as being "threshold" response, or it is a response such as 

 death which has no variation in intensity in the individual, or fixed by definition to be 

 "effective dose", etc. The potency of the test compound in this case can be defined as a 

 a measure of two factors as follows: the percentage of organisms the compound can affect 

 to that given intensity of individual response (e. g. , threshold, maximum intensity, or death) 

 and the quantity of the chemical needed to affect that number of organisms to that given 

 point. The test compound that can cause a given intensity of response in a large number of 

 organisms when administered in small quantity has a higher potency than other compounds 

 that cause the same intensity of response in a smaller number of organisms or when admin- 

 istered in larger quantity. 



In the case of either of the potency definitions ([A] quantity of compound vs. per cent intensity 

 of response in the individual organism and [B] quantity of compound vs. cumulative per cent of organisms 

 responding at a given intensity), the plotting of the two factors on graph paper results in curves 

 characteristic for any given test compound and any given response. 



For the second of these (quantity of test compound vs. cumulative per cent of organisms 

 responding), a special type of graph paper has been used, designed for correlating the two factors 

 involved, for any compound and any specific response in any organism. (See the description of the 

 CBCC Log-Probit Grid, Division 24. ) The potency of the test compound for any specific action is 

 indicated by the position of the points plotted on that Grid, relative to the positions of points plotted 

 for other compounds. 



9. Criteria 03 and 04; comparison of the test compound to a standard compound by comparing the 

 two levels of response produced by the two compounds when applied at the same dose level 

 (Criterion 03) or by comparing the dose levels, of the two compounds, needed to produce the 

 same level of response (Criterion 04) 



The discussion of Division 7 has explained why Criteria 03 and 04, like Criteria 01 and 02, are 

 used for coding intensity of positive response only when it is impossible to use other criteria, for lack 

 of proper data. It is preferable to relate the degree of biological response to fixed CBCC scales, rather 

 than to other factors such as responses of other compounds. 



It is not the intention here to imply that evaluations based on comparison to standard compounds 

 are always inconvenient except when it would add unnecessary complexity to subsequent retrieval and 

 interpretation. In a limited coding program, restricted to data from only a few test procedures, when 

 many or all evaluations are based on one or a few standard compounds with which the persons subse- 

 quently using the file would be entirely familiar, Criteria 03 and 04 might well be preferred to any other. 



Consider a test compound which caused nearly the same intensity of response as a standard 

 compound (84% compared to 87% --i. e. , both caused approximately 85% response) when administered 

 at the same dose level as the standard. The quotient of comparison would be approximately 1. 0, coded 

 by Symbol 5 in Field Y (Criterion 03); the code line for the standard compound would be coded with 

 Symbol 8 in Field Y (Criterion 62). Here, the degree of response to the test compound is actually quite 

 high (equivalent to the high evaluation for the standard compound indicated by Symbol 8), but it is not 

 revealed by the evaluation coding in Field Y except by reference to (i. e. , interpretation by) the 

 evaluation of the standard compound's performance by Criterion 62, recorded only on another punched 

 card. Consider a second example in which the test compound and a standard compound both caused 

 50% response, but the quantity of the standard compound needed to produce that response was only 

 one fourth that of the test compound. I. e. , the standard is the more "potent" of the two chemicals. 



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