36 



Indiana University Studies 



condition than the group of Kansas cities and compare favor- 

 ably with Cubberley's standard. The extremes are City A 

 with 10.3 per cent of retardation and City J with 23.6 per 

 cent. The extremes for the twelve Kansas cities are 12.8 

 and 48.2. Ayres's study and others have shown even greater 

 variability among cities. Hence we may say that this group 

 of Indiana cities shows a low amount of variability. 



Retardation 



10 20 



30 



40 



50 



60 



70 



80 



Acceleration 

 90 100 



A 10.2 



B 11.9 



C 13.6 



D 14.8 



E 15.4 



F 17.2 



G 18.3 



H 19.6 



I 20. 



J 23.6 



Av. 17.8 



Kan. 30.6 



Cub. 15.0 



Fig. 8. Sliowing average retardation and acceleration in cities liaving 

 semiannual promotion. 



