tely larger value should be assigned to each of those given.

If all six tests are given in any year group below XII, each has a value
of 2 months. If only four are given, each has a value of 3 months
(12 / 4 = 3). If five tests only are given, each has a value of
2.4 months (12 / 5 = 2.4). If in year group XII only six of the eight
tests are given, each has a value of 4 months (24 / 6 = 4). If in the
"average adult" group only five of the six tests are given, each has a
value of 6 months instead of the usual 5 months. In this connection it
will need to be remembered that the six "average adult" tests have a
combined value of 30 months (6 tests, 5 months each); also that the
combined value of the six "superior adult" tests is 36 months
(6 x 6 = 36). Accordingly, if only five of the six "superior adult"
tests are given, the value of each is 36 / 5 = 7.2 months.

For example, let us suppose that a subject has been tested as follows:
All the six tests in X were given and all were passed; only six of the
eight in XII were given and five were passed; five of the six in XIV
were given and three were passed; five of the six in "average adult"
were given and one was passed; five were given in "superior adult" and
no credit earned. The result would be as follows:--

_Years__Months_
Credit presupposed, years I to IX 9
Credit earned in X, 6 given, 6 successes 1
Credit earned in XII, 6 given, 5 passed. Unit value
of each test given is 24 / 6 = 4. Total value
of the 5 tests passed is 5 x 4 or 1 8
Credit earned in XIV, 5 tests given, 3 passed. Unit
value of each of the 5 given is 24 / 5 = 4.8.
Value of the 3 passed is 3 x 4.8, or 0 14+
Credit earned in "average adult," 5 tests given,
1 passed. Unit value of the 5 tests given is
30 / 5 = 6. Value of the 1 success 0 6
Credit earned in "superior adult" 0 0
---- ----
Total credit 13 4+

The calculation of mental age is really simpler than our verbal
illustrations make it appear. After the operation has been performed
twenty or thirty times, it can be done in less than a half-minute
without danger of error.

THE USE OF THE INTELL