FIELDS M and N 



Columns 45 and 46; 



47 and 48 



The relation between Fields M and N and Field Y will be understood by considering a single 

 symbol in Field Y, e. g. , Symbol 3, which represents a specified range of effectiveness, e. g. , 

 31-40% mortality. It frequently happens that two or more dosage levels (Fields M and N) may cause 

 responses lying within this one evaluation range (Field Y); for example, one dose may cause 32% 

 mortality while a higher dose may cause 3 9% mortality. Since either of these response evaluations 

 would be coded in Field Y with Symbol 3, they can not be distinguished by code. I. e. , the distinction 

 between 32% and 39% is beyond the discrimination given significance by the CBCC Code, by virtue 

 of the Code's having established the particular limits of this coding range as 31% and 40%. In this 

 example, all test doses producing 31-40% kill are to be coded. To state this more broadly, all doses 

 should be coded which have been shown to produce any response that falls within the definition of the 

 symbol coded in Field Y as the evaluation. 



It must be remembered that dosages in Fields M and N are also expressed by symbols repre- 

 senting ranges and reference should be made to the discussion of this under the section describing the 

 organization of these dosage fields. If all doses which produce various responses lying within a 

 single evaluation range in Field Y lie within a single dosage range in Field M or N, all of the data are 

 represented by a single code line and distinctions between the dosage levels and the corresponding 

 response evaluation are indicated only in the written abstract. If, however, the two or more doses 

 producing the responses which are coded by the same symbol in Field Y do not lie within a single 

 dosage range in Field M or N, each of the dosage ranges must be coded. This might be accomplished 

 by either of two procedures (although of the two, the CBCC has always used the more practical, 

 abbreviated procedure). To construct a separate code line for each of the dose ranges in which are 

 dose levels giving results coded by a single Field Y symbol, each line differing only by the entry in 

 Fields M and N, would be extravagant of time. As an alternative to this, the CBCC procedure is to 

 code in Fields M and N, in a single code line, all the information that would otherwise be given by 

 coding two or more separate lines. This is done by determining which doses, of all those tested, 

 produced the single optimum response evaluation coded in Field Y. If there are two such dose ranges 

 involved (e. g. , 24 and 2 5 in Field N, representing 5 mg and 10 mg), both are coded in Fields M and 

 N, by coding one above the other in the same coding box in the same line. The CBCC refers to this 

 as double coding and both entries are punched on the same IBM card. If doses which produced the 

 response coded by a single symbol in Field Y are in more than two dosage ranges (e. g. , 24, 25, 26, 

 in Field N, representing 5, 10, 25, and 50 mg doses in 4 tests), the highest and lowest ranges (e. g. , 

 24 and 26) should be coded in Fields M and/or N. 



16. Special considerations for the procedure of double coding in Fields M and N; relation of 

 Field X to Fields M, N, and Y 



Relative to the situation requiring double coding in Fields M and N, described in Division 15 

 above, is the special situation when the criterion for evaluation is based on a percentage response 

 (Criteria 51 through 59 and Criterion 62, coded in Field X) and 100% response results from administered 

 doses. When several doses have been demonstrated to produce high responses, all of which are coded 

 by a single symbol in Field Y, and one or more of these doses produce 100% response and the doses 

 producing the several responses coded by a single symbol in Field Y fall within two or more ranges in 

 Fields M and N, the CBCC considers, for coding, only those doses which produce less than 100% 

 response. For example, 5, 10, 25, 50, 100, 150, and 250 mg doses produced respectively 55%, 

 85%, 95%, 95%, 100%, 100%, and 100% responses. Since it is reasonable that optimum doses be 

 described as the lowest producing the highest response, the doses to be considered here seem to be 

 25, 50, and 100 mgs, since 100 mgs is the lowest dose producing 100% response and responses of 

 95% and 100% (produced by 25, 50, and 100 mg) are all coded by the same symbol in Field Y. However, 

 for specific reasons, the CBCC considers only doses giving less than 100%, as stated above; there- 

 fore, in this case, only 25 and 50 mg producing 95% response would be considered. Field N would 

 be double coded with Symbols 25 and 26 (the two dose ranges in which are included the two doses) and 

 Field Y would be coded with a single symbol, either Symbol 9 (when using Criterion 62 in Field X) or 

 a symbol derived by use of a special grid for correlating doses and responses of less than 100% (when 

 using any of Criteria 51 through 59). (See the special discussion, in Fields X and Y, of the CBCC 

 Log-probit Grid. ) 



It should be noted that the two criteria, 20 (Threshold Dose) and 21 (Maximum Tolerated Dose) 

 each describe a dose level which is related to a single, standard level of response. Ordinarily, this 

 is expressed as a single dose level for which reason Fields M and N would correspondingly be coded 



- 92 - 



