Section 20. Tests Belonging to the Earlier Period
It goes without saying that since the results reported were obtained from only one person they have meaning only as related to him. The question arises whether they are for this individual of a general significance—i.e., whether, by repetition of the tests at another time, they could be expected to show approximately the same amount and grouping.
A series of results from the earlier period furnishes the desired possibility of a control in this direction. They, again, have been obtained incidentally (consequently uninfluenced by expectations and suppositions) and from tests made under different conditions than those mentioned. These earlier tests occurred at an earlier hour of the day and the learning was continued until the separate series could be recited twice in succession without mistake. A test comprised
| 15 | series | of | 10 | syllables | each, | |
| or | 8 | “ | “ | 13 | “ | “ |
| or | 6 | “ | “ | 16 | “ | “ |
| or | 4 | “ | “ | 19 | “ | “ |
So, again, four different lengths of series have been taken into account, but their separate values lie much closer together.
Since the repetitions—which are in question here—were not counted at all in the earlier period, their number had to be calculated from the times. For this purpose the table on p. 31 has been used after corresponding interpolation. If the numbers found are immediately reduced to one series each, and if along with it the two repetitions representing the recitation are subtracted as above, we obtain:
| Number of syllables in a series |
Number of repetitions necessary for two errorless reproductions (exclusive of them) |
Probable error[1] |
Number of tests |
| 10 | 13 | ± 1. | 16 |
| 13 | 23 | ± 0.5 | 92 |
| 16 | 32 | ± 1.2 | 6 |
| 19 | 38 | ± 2.0 | 11 |
- ↑ The probable errors are based upon calculation and have only an approximate value.
