The essentials of mental measurement / by William Brown.

  • Brown, William, 1811-
Date:
1911
Catalogue details

Licence: In copyright

Credit: The essentials of mental measurement / by William Brown. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    136/172 (page 124)
    Thus the original positive correlation between anos and motor is due entirely to the correlation of each with er. For er constant, the correlation is large but negative, in all three cases. Employing the four variables. School Marks, General In- telligence, Combination and Mechanical Memory (Group II) and using the formula ^12 (1 ^'^34) ~ ''^13 (^'23 ^24^^34) ~ ^t4 (^24 ^23^34) ?*]2 34 — . ~ — , ■ '■ t V1 - r^, - ? - r^34+27^13 V1 - r\, -r\^- r'^+2 r.^ r.^ (see p. 64), I find the correlation between Combination and General Intelligence, assuming constant ability in Mechanical Memory, and as shown by School Marks = 0-11 ±0-11. The entire coefficients = 0-43 + '09. It is interesting to note that there is still correlation, though very slight, after the effect of memory and school industry and abihty is eliminated. A more thoroughgoing application of the method of partial correlation was made in the case of Group I, for the tests er, anos, Combination and Mechanical Memory. The full working, according to Mr G. U. Yule's method, is given in Appendix III. The results were: Tests Correlated e r, ca 110 s er, Combination er, Mechanical Memory anos, Combination anos, Mechanical Memory Combination, Mechanical Memory The regression equation for the calculation of ability in combination from abilities in the other three tests is Wf. = •002it;er + 'CQQiranos + 'TOS/CHicch. memory. X in each case denoting deviation from mean ability. For a larger number of variables than four, the arithmetic of partial correlation becomes extremely lengthy and rather fatiguing, but there can be no doubt whatever that this is the one sound method to adopt in investigatuig the relations Entire Partial Coefficients Coefficients 0-78 ±-03 0-73 ±-04 0-45 ±-07 0-01 ±-09 0-40+-07 0-26 ±-08 0-48 ±-07 0-27 ± -08 0-29 ± -08 -0-15 ±-08 0-52 ±-06 0-44 ±-07