48 BELL SYSTEM TECHNICAL JOURNAL 



Key to the Charts 



The charts present various graphical representations of the function 

 W{c, X, n, N), equation 3. This function gives the probability, W, 

 that the number of defectives in a lot of N is equal to or less than X, 

 after a sample of n units has shown c defectives, assuming that each 

 of the possible values of X between o and N were equally likely a priori. 



Charts A: Separate pages refer to different values of n and N as 

 labelled. 



Ordinates, W; abscissas, X. 



Solid curves, r; dotted curves (c/n — X/N) expressed as per cent. 



Charts B: Separate groups of curves refer to different values of W 

 as labelled. 



Ordinates, X/N; abscissas, n. 



Separate sets of curves in each group refer to different values of 

 c/n as labelled. 



Individual curves are for different values of N. 



Charts C: Separate pages refer to different values of W. 



Ordinates, n; abscissas, n/N. 



Separate curves for different values of c. 



Cross-hatching indicates amount of dependence on X/N. For 

 fuller explanation see pages 34—37 incl. 



