500 n 



r20 



19 



18 

 1-17 



16 

 1-15 



14 

 -13 

 -12 



11 

 -10 

 -9 

 -8 



7 



6 

 -5 

 -4 



3 

 -2 

 -1 



c 



3 



o 



a 



-D 



c 



3 



E 



a 

 to 



I I I I I I I I I I l| I I I I II I I I I I I I I I |l M | l I l| I I l | I I l |l I I I I I l| I I l | I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I 



SALES J FMAMJ J ASONDJ FMAMJ J ASOND 



COST 1967 1968 



Appendix Figure 8.— Fresh sole fillets — weekly retail prices, purchase costs, and sales volume from a Chicago food chain store with 20 



branches, 1967 and 1968. 



30 



