FIELDS W, X, and Y 



Columns 68; 69 and 



70; and 71 



expresses the evaluation in terms of the percentage of response in the individual. "Field X has no 

 criterion which correlates this intensity of response in the Individual with the minimum dose needed 

 for that intensity, with the possible exception of Criteria 20 and 21 which can be considered to base 

 evaluation on dose size alone yet express potency when the response intensity can be ignored. (See 

 Divisions 14 and 15. ) Criterion 61 and 62 are used to evaluate synergism as described in Division 22. 



Criterion 62 is used for all negative data expressed at 0% response. (All other negative re- 

 sponse expressions, either verbal ["inactive", "no response", etc. ] or author's scoring symbol 

 ["0", "-' , etc. ] are coded by Criteria 01 and 02. ) 



The CBCC has also used Criterion 62 for another evaluation expression- -the percentage of 

 individuals (of a group) responding to the test compound (at a given level of intensity of response in 

 the individual). This is distinct from the expression "percentage of response intensity of which an 

 individual is capable" and therefore it is suggested here that, for the expression "percentage of 

 organisms responding at a given response intensity", a unique code symbol (i. e. , a distinct criterion) 

 should have been established (e. g. , a criterion designated as 63). This use which has been made of 

 Criterion 62 is described in the following paragraph. 



It will be noted that whenever a group of organisms is administered the test compound at a 

 given dosage level (a "population study") and the incidence of response is recorded as the result of 

 the test (i. e. , the percentage of individuals responding at that dose level and that intensity of indi- 

 vidual response), the Log-Probit Grid is used to correlate the percentage of organisms responding with 

 the minimum dose affecting that percentage of organisms to the given degree ("potency" as defined in 

 Subdivision B of Division 8). For this, Criteria 51, 52, and 53 are most frequently used, though 

 Criterion 55 is also established to correlate the percentage of organisms in which a given dose of test 

 compound antagonizes a secondary compound to a given intensity in the individual (100%); also, 

 Criteria 54, 57, 58, and 59 use this Log-Probit Grid, not to derive an expression of potency, but to 

 correlate duration of a specific action, time to a specific action, etc. , with the incidence of the 

 duration of action, time to specific action, etc. , in a group of individuals all of which are administered 

 the same dose. (See Division 20. ) However, evaluations have been made by the CBCC based solely 

 on the incidence of a given response intensity in a group of individuals, disregarding the quantity of 

 test compound, coded in Fields M and N, needed to accomplish that incidence, using Criterion 62, as 

 indicated above. In order for such evaluations to be meaningful (in terms of being subsequently able 

 to compare test compounds for a specific action), it should be assumed that the test of each compound 

 has demonstrated the maximum percentage of organisms the compound is capable of affecting to the 

 given intensity. (Field W should therefore be coded with Symbols N, 0, or P according to whether 

 the dose has been demonstrated to be the minimum needed). If the percentage of organisms affected 

 has not been demonstrated to be the maximum number the test compound can affect (Field W coded with 

 only Symbol L or P), evaluation of the test compound's potency by correlating coding of Field Y with 

 that of Fields M and N is more uncertain. 



24. The Log-Probit Grid; Use of the Grid with Criteria 51, 52, 53, 54, 55, 57, 58, and 59 



Each of the criteria which base evaluation on the Incidence of the specific response in a group 

 (or "population") of individuals is discussed separately; see Division 19 (Criteria 51, 52, and 53), 

 Division 20 (Criteria 54, 57, 58, and 59), and Division 21 (Criterion 55), as well as Division 22 

 (Criterion 62), since Criterion 62 is used to evaluate on the basis of the percentage of individuals 

 responding. Reference should also be made to Division 8, particularly the Subdivision B. 



Of these criteria, eight (i. e. , all except Criterion 62) are concerned with a second factor, 

 either (a) the minimum dose needed to cause the demonstrated incidence of response or (b) the time 

 factor involved in the measurement of the test compound's action (e. g. , time to specific action, 

 duration of response, etc. , coded in Field U) as related to the incidence of that time factor in a group 

 of individuals. The first of these, (a), represents the second factor for Criteria 51, 52, 53, and 55, 

 while the last, (b), represents the second factor for Criteria 54, 57, 58, a"d 59. 



To correlate the two factors involved in each of these criteria in a way that will provide a 

 basis for comparative code evaluation, the CBCC has established a single evaluation reference chart, 

 using a special graph paper, most frequently referred to as probability paper. The unique feature of 

 this paper is its vertical scale (the ordinate) which is neither arithmetic nor logarithmic; the paper 



205 



