500 



150 



100- 



50 



r 



-20 



-19 



-18 

 17 

 16 

 15 

 14 

 13 



-12 



-11 

 10 



1-9 

 8 

 7 



-6 



-5 

 4 

 3 



-2 



-1 



TO 



c 



o 



a 



(U 



3 



0) 



E 



J) 

 J? 



I ' I I I I 1 j I 111 II ' j T- T T p ' ' I ' " ' pT r ■ 1 I T I I I I I ? r I I [ T ■ n I I | | M I I I | I i ( I I I ' I T I I I ■ i i I i i i | i i i I i i r F I i I | | | I 



SALES J FMAMJ J ASONDJ FMAMJ J ASOND 



1967 1968 



PRICE 

 COST 



Appendix Figure 7. — Frozen sole fillets — weekly retail prices, purchase costs, and sales volume from a Chicago food chain store with 



20 branches, 1967 and 1%8. 



29 



