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THE BELL SYSTEM TECHNICAL JOURNAL, MARCH, 1954 



It became necessary, therefore, to develop these relationships from 

 empirical data. Accordingly extensive field studies were conducted in a 

 number of toll offices of different sizes to determine whether there was 

 any consistent relationship between group and office busy-hour load 

 levels of the many groups. Examination of group and office busy-hour 

 loads on a total of almost 300 groups in 6 different offices showed a defi- 

 nite relationship which could be expressed as a function of a given value 

 of group busy-hour load. Fig. 9 shows the group to office ratios finally 

 computed from these data for use in the nationwide trunk study. The 

 ratios for the smaller loads (30-90 CCS) showed considerable lack of 

 consistency as between offices, but an adeciuate set of ratios for these 



1000 

 900 

 800 

 700 

 600 

 500 



400 

 300 



70 



20 



1.6 1.5 1.4 1.3 1.2 1.1 1.0 



RATIO OF GROUP BUSY HOUR TO OFFICE BUSY HOUR 



Fig. 9 — Relationship between group busy hour and office l)us\- hour loads on 

 intertoll trunk groups. 



