Professional group 85%
Executive group 68%
Artisan group 41%
Labour group 39%

In the "Journal of Educational Psychology," Vol. IX, 1916, Mr. A.W.
Kornhauser gives evidence from the examination of 1,000 children drawn
from five schools in Pittsburgh.

Schools A and B were attended by children of unskilled manual workers.

Schools C and D by children of skilled artisans and small shopkeepers.

School E by children of parents in very comfortable circumstances.

The results are tabulated as--

Retarded, _i.e._, below average.
Normal, _i.e._, average.
Advanced, _i.e._, above average.

| Retarded. | Normal. | Advanced.
A } Manual workers {| 45.2 | 47.1 | 7.7
B } {| 36.7 | 55.9 | 7.4
| | |
C } Artisans, etc. {| 29.4 | 50.2 | 20.7
D } {| 28.8 | 50.2 | 19.5
| | |
E Most comfortable | 12.7 | 62.7 | 24.6[A]