Strangely enough, decrease in fatigueability as described in the previous chapter does not show itself after 12 months. In fact, the negligible loss in ability noticeable after six months has increased after a period of twelve months. In only 4 out of 11 test group cases, is the gain in the second period equal to that of the first, a similar result to that found in the control group, where 5 out of the 11 cases made half their total gain in the second interval. The results are compared below.
| 6 months | 12 months | |
| Average of gains of test group in excess of control | -·020 | - ·060 |
| Median of gains of test group in excess of control | -·015 | - ·090 |
| P. E. of difference | ±·040 | ± ·036 |
| Average in terms of P. E. | -·500 | -1·660 |
| Median in terms of P. E. | -·380 | -2·500 |
TABLE XX
Tapping for Fatigue, Second Retests, 11 Pairs
| N[16] | Test Group (A) | Control Group (B) | |||||
| Test 1 | Test 3 | Gain | Test 1 | Test 3 | Gain | A-B | |
| 20 | -·10 | ·03 | -·13 | ·20 | ·0 | ·20 | -·33 |
| 27 | ·15 | ·17 | -·02 | ·09 | -·17 | ·26 | -·28 |
| 10 | -·09 | ·27 | -·36 | ·06 | ·16 | -·10 | -·26 |
| 14 | ·09 | ·05 | ·04 | ·13 | -·13 | ·26 | -·22 |
| 13 | -·03 | -·06 | ·03 | ·27 | ·07 | ·20 | -·17 |
| 28 | ·01 | ·05 | -·04 | ·17 | ·10 | ·07 | -·11 |
| 15 | ·03 | ·03 | ·0 | ·18 | ·08 | ·10 | -·10 |
| 23 | ·11 | ·0 | ·11 | ·06 | ·0 | ·06 | ·05 |
| 21 | ·27 | -·01 | ·28 | ·29 | ·14 | ·15 | ·13 |
| 11 | ·28 | -·04 | ·32 | ·11 | -·01 | ·12 | ·20 |
| 18 | ·14 | -·15 | ·29 | ·01 | ·15 | -·14 | ·43 |
| Av. | ·078 | ·031 | ·047 | ·143 | ·035 | ·107 | -·06 |
| M | ·03 | ·12 | -·09 | ||||
| 75%ile | ·153 | ·20 | ·07 | ||||
| 25%ile | -·062 | ·02 | -·275 | ||||
| Q | ·107 | ·09 | ·172 | ||||
| P. E. (distribution) | ·087 | ·093 | ·19 | ||||
| P. E. (average) | ±·02 | ±·03 | ±·036 | ||||
| Av.=-1·66 P. E. | |||||||
| M.=-2·50 P. E. | |||||||
The point of greatest interest in the present study is, as has been said, improvement in intelligence. Does operation for adenoids and tonsils result in improvement in intelligence, as measured by I.Q.? If such improvement does not manifest itself after six months, can it be found after a second period of the same length? The latter question is answered by observation of Table XXI and attention to the following facts, gathered from the 21 pairs of cases who were given intelligence tests after the twelve months' interval.
| 6 months | 12 months | |
| Average of gains of test group in excess of control | -1·035 | -3·14 |
| Median of gains of test group in excess of control | -1 | -3 |
| P. E. of difference | ±1·10 | ±1·84 |
| Average in terms of P. E. | - ·94 | -1·71 |
| Median in terms of P. E. | - ·99 | -1·63 |
The result after twelve months remains the same as that after the six months' interval. A gain or loss of two or three points in I.Q. is negligible, so that the mean gain of the test group in excess of the control is practically zero at the end of each period. Variability increases with the length of the interval. One case in the test group (case 4) gained nothing in six months, but showed a gain of 15 points after 13 months. However, there is a control case to match this,—case 15, who gained 1 point in the first six months and 20 points after 10 months. Case 20 in the test group lost 4 points in the first six months, but gained back these and 10 additional in the second period. But control No. 1 gained 5 points in the second interval after having lost 4 in the first.
On the other hand several cases lost in the second period, as compared with the first. Test group case 7, for example, gained 8 points in the first six months, and lost 6 of them in the second. Case 3 in the same group lost 3 points in the first period, and failed to regain any of them. Case 12 lost 3 points in six months and 9 more before the end of 12 months. In the control group, case 23 gained 15 pounds in the first six months and lost eight of them in the second. Summing up gains and losses in the second period, for both groups: