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MEMOIRS NATIONAL ACADEMY OF SCIENCES. 



[Vol. XV, 



If we take the agreement of one test with all the others as our standard of excellence, 

 then we are interested in the changes of correlation from row 6 to row 7, for, subtracting row 

 6 from row 7, we get the differences between the coefficients of each test, single time, with total 

 score, single time, and each test, double time, with the same. These differences are: 



Arranging the tests in the order of these differences from the greatest to the least we have 

 2, 4, 8, 7, 6, 3, 5. 



It may be argued, however, that these correlations are not quite fair to double time, since 

 we are actually correlating the single time scores with a total of which they are a part. To 

 meet this objection each test, single time, was correlated with the total scores of the remaining 

 seven tests. Then double time on each test was correlated with the same total. The results, 

 as expressed in differences obtained by subtracting row 8 from row 9 in table 76, are: 



Arranging the tests in the order of the differences from greatest to least we have 2, 4, 8, 7, 

 6, 3, 5. This is exactly the same order as above except for the tie between tests 6 and 3, but 

 the differences are more in favor of double time. On the basis of the above correlations double 

 time could not be recommended on any test except test 2. 



Table 78. — Per cent who gained at each level of the various tests. 



