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BELL SYSTEM TECHNICAL JOURNAL 



therefore result in calculated values of the probability of lockout which 

 are proportional to the desired probability, and if the value of the 

 integral calculated from their data is p, then 



P = kp, 



(2) 



where ^ is a constant of proportionality which depends on the average 

 number of pauses occurring, and which can be determined by comparing 

 observed and calculated results. 



The observed lockouts per hundred seconds plotted against the cal- 

 culated probability of lockout for each circuit condition are shown in 

 Fig. 5 for lasting lockouts and in Fig. 6 for releasing lockouts. The 



0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 



CALCULATED PROBABILITY 



Fig. 5 — Observed lasting lockouts vs. calculated probability. 



data are separated in this way, since the factor of proportionality be- 

 tween observed and calculated results is found to be different for the 

 two cases. This is probably due to the fact that the method of deter- 

 mining response and resumption times was such that some of the nega- 

 tive and shorter positive response times could not be detected. An 

 increase in the number of these response times would result in an in- 

 creased probability of releasing lockouts, which would tend to bring the 

 two sets of data into agreement. Greater accuracy might be obtained 

 if the distribution of response times were to be more accurately deter- 

 mined, but the present data are sufficient for approximate calculations. 

 In both figures the data obtained in a single group of tests are con- 

 nected by dotted lines. The solid lines are the best estimates to repre- 



