24 MASS. EXPERIMENT STATION BULLETIN 389 



Summary data are given in table 16A. The three basic shippers' prices were 

 used in the comparison, and with each type there were highly significant differ- 

 ences between the group means. Differences of this size then could be caused 

 by variation in the ratio of ratings to deliveries. Since the removal of other 

 possible causes of variation by systematizing was associated with an expansion 

 of "F," the significance of ratings as a cause of price differences was very pro- 

 nounced. 



Whereas ratings had a decided influence on the prices received by shippers 

 selling to dealer A, they had no common effect on the prices received by the 

 shipper to dealer B. The results of the analysis are given in table 16B. In no 

 instance did "F" equal 1 percent or 5 percent values which would indicate ratings 

 as a basic cause of price variation. Additional weight was afforded this con- 

 clusion by the irregular adjustments in the value of "F" as prices were systemati- 

 cally refined. For all practical purposes, dealer B might as well have been on the 

 straight use plan so far as the prices to his shippers were concerned. 



Seasonality of production under the conditions which prevailed in the Spring- 

 field market had no significant effect on producers' prices. The adjusted data 

 were not subjected to any test other than that of observation. The data for all 

 three groups, table 17, were so nearly' comparable that apparently little could 

 be gained by an extended analysis. 



Frequency distributions of the prices received by grade B shippers are given 

 in table 18. The mid-point of the modal price class was 5.5 cents per quart for 

 both the actual and the 3.7 standardized fat basis; the mid-point of the modal 

 price class on a 3.7 standardized F.O.B. basis was 6.25 cents per quart, indicating 

 an average trucking charge of 35 cents per hundredweight. 



A summary of the characteristics of the various types of prices is given in 

 table 19. 



