The coefficient found between the teacher’s estimates of intelligence and the results of educational measurements, .51, indicates a really useful degree of coördination. Unless a Mentimeter test shows a coefficient of coordination of .25 or more with the production records (or other reliable measure of true ability), it may be considered as having little value in helping to select and differentiate men for that particular line of work. If the coefficient is above .5, the test is quite useful, and the nearer the coefficient approaches 1.00 the more confidence one may place in the test as a means of selecting and classifying men in that particular field. The sixth column of the table on page 329 gives the difference between the test results rankings and the scholarship marks rankings, and the seventh column gives the squares of these differences, the sum of these squares being given at the bottom of the seventh column as 1411.5. By substituting in the formula, ρ = 1 − (6Σd^2)/(n(n^2 − 1)) = 1 − (6 × 1411.5)/(28 × 783) = 1 − 8469./21924. = 1 − .386 = .614, it appears that the tests more closely correspond with the average of the scholarship marks given by the teacher than with the teacher’s estimate of intelligence. This is partly to be explained by the fact that the tests given were measurements of ability in school subjects rather than tests of intelligence, and still more by the fact that the teacher gave scholarship marks on the basis of relatively objective examinations while her estimates of intelligence are always wholly subjective. The eighth and ninth columns on page 8 give the differences between the ranks in the teacher’s estimates of intelligence and the ranks in the scholarship marks given during a half year. The coefficient of coördination worked out from these differences is .833 (ρ = 1 − (6 × 611)/(28 × 783) = 1 − 3666/21924 = 1 − .167 = .833) which would seem to indicate that the teacher drew very heavily on her knowledge of the relative scholarship of her pupils in making her estimates of their intellectual capacities. The three coefficients worked out above for 28 pupils in a sixth grade are typical of the mathematical relationships the reader will wish to work out between known degrees of ability in a certain type of work and the results of the Mentimeter tests. The coefficients of coördination for the sixth-grade pupils studied above are, between Educational Measurements and Estimated Intelligence = .51 Educational Measurements and Scholarship Averages = .61 Estimated Intelligence and Scholarship Averages = .83 No method of forecasting degree of success in one line of work from quality of performance in another task (or in a test) will give a perfect coefficient of coordination of 1.00, but the nearer the coefficient approaches 1.00 the more reliance one may put in the test which furnishes such a ranking of the individuals.