110 



THE ACQUISITION OF SKILL IN ARCHERY. 



All group records, each based upon 20 successive shots, are included in 

 table 39, but for the computation of the amount of improvement it has 

 seemed best to use averages based upon as large a number of shots as 

 possible. The simplest method, and the one which probably gives the most 

 dependable results where comparisons are made of the total amount of im- 

 provement in a given amount of practice, is that of using the average of all 

 shots during the first half of practice as an index of the initial accuracy, and 

 the average of all during the second half as an index of final accuracy. 



TABLE 33. Relative amount of variation in records of shots during successive practice 

 periods for one subject of the 12-shot group. 



The chief objection to this method is that it assumes a like form for the 

 learning curves of the groups compared and does not give sufficient weight to 

 rapid initial improvement, final spurts, or similar variations in the rate of 

 learning. To meet this objection the improvement from the first to the last 

 5 and from the first to the last 40 shots has also been computed and com- 

 pared with that obtained by the first method. 



In comparative studies of learning, the further question of the relative value 

 of the absolute amount of improvement and the percentage improvement, in 

 terms of initial skill, arises. It seems to the writer that the use of percent- 

 ages is justified only when it is clear that each step in learning presents the same 

 difficulty to all individuals compared. If the first stages of learning present, 

 for the individual with a low initial skill, the same difficulty as do the second 

 stages for the individual with greater initial skill, then the absolute improve- 

 ment would seem a more accurate measure for the effects of such factors as 

 distribution of practice. Figure 11 shows the relations of initial and final 

 skill in archery for the individuals studied. On the average, the absolute 

 improvement of those of low initial accuracy was little greater than that of the 

 others, which indicates that the problem really presented greater difficulties 

 for them throughout, 



In the case of rifle practice this does not seem to be true. Figure 12 shows 

 that individuals of low initial accuracy made by far the greater absolute 

 improvement, and in this case it seems that the percentage rather than the 

 absolute improvement should be used in comparison of the groups. 



