(5 and 6). Height-Strength of Arm. For both boys and girls the correlations between the yearly measurements of height and strength of the arm are lower than between height and any of the other physical traits measured except the strength of the upper back.

Height bears about the same relation to strength of the right arm as to strength of the left arm. The correlation is high for boys at eight and nine years, but drops to +497 for the right arm and +443 for the left at 12 years. The coefficients increase to + .655 for the right at 13 years and +672 for the left at 14 years. After that time the correlation coefficients decrease to +.440 and + .384 for left and right arm, respectively, at 17 years. The relation between height and strength of the arm for girls is very irregular. At seven years, the coefficients are + .801 with the right arm and +793 with the left arm. They decrease to +423 and + .396 at 10 years, increase again to +.574 for the right arm at 14 years and +.524 for the left at 13 years. They decrease to +208 and +.137 at 17 years. The averages of the coefficients are: height with right arm.568 for boys and + .521 for girls and with left arm + .517 for boys and + .444 for girls.

(7) Height-Strength of Upper Back. The correlations between the yearly measurements of height and strength of the upper back are lower than the correlations between height and the other six physical traits at all years in the case of the boys and from seven to 11 years in the case of the girls. After 11 years, these correlations for girls are higher than with the strength of the arms and the girth of the chest.

For the boys, the coefficient of correlation is +.300 at eight years, rises to .636 at 11 years, drops to + .587 at 14 years and drops rapidly to the minimum, +234 at 16 years. There are no such marked differences in the correlation coefficients of the girls from year to year. The coefficient is + .606 at seven years, decreases to +408 at 10 years, rises to + .567 at 13 years, and is + .343 at 17 years. The averages of the coefficients are + .462 for boys and + .475 for girls.

(8) Weight-Breathing Capacity. The correlations between the yearly measurements of weight and height, sitting height, and girth of chest are higher than with breathing capacity for both boys and girls.

The correlation is highest for the boys at seven years (+.801) and

at eight years (+.695.) The coefficient gradually increases to +.787 at 15 years and is +.617 at 17 years. The correlation between weight and breathing capacity is not high for girls and there is much wider variation from year to year. The coefficient drops from.643 at eight years to + .434 at nine years and then gradually increases to the maximum (+.620) at 12 years. The minimum (+.318) is reached at 15 years. The averages of the coefficients are.730 for boys and + .517 for girls.

(9) Weight-Sitting Height. The coefficients of correlation between the yearly measurements of weight and sitting height are almost the same as those of weight and height, though slightly lower. They are also lower than the coefficients between weight and the girth of the chest.

With the boys, the coefficient is +.858 at nine years and +.739 at 12 years, + .837 at 14 years, and decreases to +.607 at 17 years. With the girls, the coefficient increases to +.692 at 14 years and then drops to .510 at 17 years. The averages of the + coefficients are +.785 for the boys and + .588 for the girls.

(10) Weight-Girth of Chest. Between the yearly measurements of weight and the girth of the chest the correlations are higher than for weight and any other physical trait measured.

The coefficients are fairly uniform throughout the ten years, varying from .793 at nine years to.897 at 14 years for the boys and from + .927 at nine years to .851 at 17 years for the girls. The averages of the coefficients are +.859 for boys and .895 for girls.

(11 and 12) Weight-Strength of Arm. The correlation coefficients between the yearly measurements of weight and strength of the arm are lower than between weight and height, breathing capacity, sitting height and the girth of the chest.

For the boys, the coefficients between weight and strength of the right arm are slightly higher than between weight and strength of the left arm. The coefficients vary from +.796 and +.643 for right and left respectively, at eight years, to +.577 and +.541 at 12 years. The coefficient increases to +.733 (weight with right arm) at 15 and

797 (weight with left arm) at 16 years and then drops to .586 and + .408 at 17 years. For the girls, the coefficients vary from +.540 and .529 at seven years to .429 and 400 at nine years, increase to the maximum + .641, at 13 years (right arm) and .569 at 12 years (left arm), and then

gradually decrease to + .361 and + .258 at 17 years. The averages of the coefficients are: weight with strength of the right arm, .671 for boys and +.498 for girls, and with strength of the left arm, +.619 for boys and +.438 for girls.

(13) Weight-Strength of Upper Back. The coefficients between the yearly measurements of weight and strength of the upper back are lower than any of the other weight correlations.

The coefficient drops from +.681 at seven years to +442 at eight years, increases at 11 years and decreases again at 12 years. It reaches the maximum + .698 at 14 years and then decreases to +402 at 17 years. With the girls, the coefficient drops from + .433 at seven years to +351 at 11 years, then increases to + .538 at 14 years, followed by a decrease. The averages of the coefficients are575 for boys and +425 for girls.

(14) Breathing Capacity-Sitting Height. The correlation coefficients between the yearly measurements of breathing capacity and sitting height are very much like those between breathing capacity and standing height, though slightly lower. They are higher than the coefficients of correlation between breathing capacity and the five other physical traits.

For the boys, the coefficient decreases from +.843 at seven years to.690 at 10 years, increases to + .818 at 15 years and then drops to 535 at 17 years. For the girls, the coefficients are very irregular, alternately high and low. The maximum coefficient is + .762 at 13 years, and the minimum is + .430 at eight years. The averages of the coefficients are +.745 for boys and +.631 for girls.

(15) Breathing Capacity-Girth of Chest. The correlations between the yearly measurements of breathing capacity and girth of the chest are not so high as those between breathing capacity and height, sitting height and weight.

For the boys, the coefficient drops from +.768 at seven years to 621 at eight years, increases to +.740 at 15 years and then decreases to +. 634 at 17 years. For the girls, the coefficient increases from +.536 at seven years to +.717 at eight years, drops to.419 at nine years, increases to +.540 at 13 years and then drops to 439 at 17 years. The averages of the coefficients are .690 for boys and +.500 for girls.

(16 and 17) Breathing Capacity-Strength of Arm. The coefficients of correlation between the yearly measurements of breathing

COEFFICIENTS OF CORRELATION

.70

capacity and the strength of the arm are lower than those between breathing capacity and height, sitting height, weight and girth of the chest.

For boys, the coefficients between breathing capacity and the right and the left arm change from +.595 and +.506 at seven years, to +.523 and +.556 at nine years, increase to +.663 and +.682 at 14 years, then drop to .428 and + .342 at 17 years. The coefficients are much more irregular from year to year for the

70

Boys CORRELATIONS

FOR BREATHING CAPACITY WITH

I-HEIGHT

2-WEIGHT

3-SITTING HEIGHT--

4-GIRTH OF CHEST

5-STR. RIGHT ARM

6-STR. LEFT ARM

7-STR. UPPER BACK···

girls, alternately high and low. At seven years, the coefficients are +.694 with the strength of the right arm and +.572 with the strength of the left arm. There is very little correlation after 14 years. The coefficients drop to +.163 and +.120 at 17 years. The averages of the coefficients are: breathing capacity with strength of the right arm, + .569 for boys and + .420 for girls; with strength of the left arm, +.526 for boys and +.380 for girls.

(18) Breathing Capacity-Strength of Upper Back. The coefficients of correlation between the yearly measurements of breathing capacity and strength of upper back are lower than the correlations of breathing capacity and the other six traits for boys and for girls,