TABLE 12
AMOUNT OF OVER– AND UNDER–ESTIMATION OF INTERVALS
| Males. | Females. | Males. | |||||||||||||
 | I | – 0.3 | + 2.74 | Age | 17 | 18 | 19 | 20 | 21 | 22 | 23 | ||||
| E | + 1.5 | + 7.55 | Over– or under– | ||||||||||||
| 18˝ | R | – 2.5 | + 0.46 | estimation | – 3.60 | – 7.50 | –13.02 | –13.49 | – 8.71 | –13.20 | – 8.55 | ||||
| W | – 6.5 | – 2.42 | No. + | 6 | 2 | 2 | 0 | 2 | 2 | 2 | |||||
 | I | – 2.7 | + 6.81 | No. – | 10 | 14 | 14 | 16 | 14 | 14 | 14 | ||||
| E | – 2.9 | + 5.54 | |||||||||||||
| 36˝ | R | – 3.9 | + 5.71 | ||||||||||||
| W | –11.3 | – 5.90 | Females. | ||||||||||||
 | I | – 8.7 | + 1.00 | ||||||||||||
| E | – 8.9 | + 5.13 | Age | 17 | 18 | 19 | 20 | ||||||||
| 72˝ | R | –18.1 | – 1.22 | Over– or under– | |||||||||||
| W | –24.8 | –17.07 | estimation | + 2.38 | – 4.16 | – 2.57 | + 2.55 | ||||||||
 | I | –15.3 | + 5.37 | No. + | 11 | 8 | 8 | 12 | |||||||
| E | – 8.2 | + 6.88 | No. – | 5 | 8 | 8 | 4 | ||||||||
| 108˝ | R | –17.9 | – 7.53 | + = overestimation | |||||||||||
| W | –32.5 | –20.55 | – = underestimation | ||||||||||||
In Table 13 are the means, variabilities, errors, etc., for the letter-counting tests. In this table we have presented the values of the various statistical quantities for the several ages of both males and females, for there are certain interesting differences which should be noted. Similar age-tables have been prepared for all of the other results, but in no case have noteworthy differences appeared. From Table 13 it will be observed that the males on the average count more letters in thirty seconds than do the females, and at the same time make more errors. The mean and relative variabilities for the sex-groups are almost the same. Curiously enough the number of letters counted as well as the accuracy of counting decrease for the females with age (17 to 20 years being the age-limits of the group under consideration). The males within the same age-limits increase in rapidity of counting, but decrease in accuracy. In the examination of Table 13 it is to be remembered that the 17 and 23 year groups of males contain only 16 individuals each, and therefore cannot be compared to advantage with the other groups. Both mean and relative variabilities decrease from 17 to 20 years for the females, whereas for the males there is no constancy in the direction of the change.