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THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1954 



Table I — Design of Graeco-Latix Square Experiment 

 Each run made with the "x" bins loaded with 0, 50, 85 and 100 cards 

 and consists of four operations (A, B, C, D) of each coded card. 



Bin No. 



Photocell 

 Mounting 



Lamp 



Position in Bin 



variables of the list. The layout of these variables in the Graeco-Latin 

 Square design is given in Table I. 



The remaining two variables are functions of different portions of the 

 machine. The rows of the Sciuare, involving distribution of coded and 

 uncoded cards, represent distinct machine set-ups, and hence if for 

 every set-up the load of the seven not-measured bins is varied, and for 

 every variation in this load 4 observations of the 5 pairs are taken, 



