The essentials of mental measurement . nown with certainty to be uncorrelated with each other and with the truevalues, yet, with such small numbers of cases as are used in many of thepsychological researches in which Professor Spearnmns formula has beenemployed, the chance of, S (x^y^) being nearly equal to S [x^^ isexceedingly small, and it is difficult to attach any meaning to an artificial,post hoc separation of the data into halves such that this condition issatisfied (and also others). The formula is at any rate inapplicable tosamples such as 30, 24, 52, which have been freely used i
The essentials of mental measurement . nown with certainty to be uncorrelated with each other and with the truevalues, yet, with such small numbers of cases as are used in many of thepsychological researches in which Professor Spearnmns formula has beenemployed, the chance of, S (x^y^) being nearly equal to S [x^^ isexceedingly small, and it is difficult to attach any meaning to an artificial,post hoc separation of the data into halves such that this condition issatisfied (and also others). The formula is at any rate inapplicable tosamples such as 30, 24, 52, which have been freely used in experimentalwork; or if used at all, it can only be as a guide to the sufficiency of thesample. It is an essential of good work to use such samples that correc-tions to the raw values obtained are unimportant. Regression Curves of Correlation Table* >? Errors made, in mm. -gS-21. -18-7 -IS -13 -11 -9 -7 -5 -3 -? +1 ^ B 7 9 11 13 IS 17 19 51 aa I 30 X 36 40 a ^a •« •9 60w ?M o 80 DO :S 65 g 70Hi70 SO&s 909S 10D -r 1 r. Fig. 27* See pp. 162—3. B. &X. 11 162 CORRELATION [ft. II CO fS g 5 -2 s r Si, O o JO « EH co o o to H H m 72-5 + •507 -^I (MCDd5(i)^CO-^C0-^^-^ 10 iM 5 + 07 + »0 <N (M (M t* co^i>ibi>(Nioi>cbco(NQb-4t»o 1-1 r-( rH COso i i 1 CC CO CO C^ (N »0 »0 (N r-10 CO Tt—( ^ + I (MA CO (N 1. CO T^ ?I rt| 1 1 1 |rtTf + CO 1 M 1 M 1 1 1 1 1 1 M 1 1 0 U50»«0»r50iOO»00»nO»00 C0^^lOlOCDCOt*l>G000OSO5i--l ff0C0Tt<SlO»O©t>00000J05 12 Ji E-i a -H CO II r-l 50 O 05 l> 00 <N CO II II •tntn tn 8ani[ jo sq^Suaq; CH. VIII] CORRECTION OF CORRELATION COEFFICIENTS 163 f
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Keywords: ., boo, bookcentury1900, bookdecade1920, booksubjectpsychophysiology
