298 



Journal of Agricultural Research voi. xvn.No. e 



VARIATION CONSTANTS 



Before undertaking any discussion of the distributions given in Tables 

 I and II it is desirable to have at hand the simple physical constants, 

 means, standard deviations, and coefficients of variation deduced from 

 them. These constants are accordingly given in Tables III and IV. In 

 the calculation of the standard deviations vSheppard's correction of the 

 second moment was used in all cases. 



Table III. — Constants for variation in weekly milk yield 



Age of cow. 



6 years. 



8 years. 



16 years. 



Weighted means (total) 



Year. 



1908 



1909 



Combined. 



1908 



1909 



Combined, 



1908 



1909 



Combined. 



1908 



1909 



Combined. 



1908 



1909 



Combined. 



1908 



1909 



Combined 



1908 



1909 



Combined. 



1908 



1909 



Combined 



1908 



1909 



Combined 



1908 



1909 



Combined 



1908 



1909 



Combined 



1908 



1909 



Combined 



1908 



1909 



Combined 



1908 



1909 



Combined 



1908 



1909 



Combined 



Mean weekly 

 yield (in 

 gallons). 



3. 907±a 274 

 3. 407± -243 

 3. 6io± . 183 



4. 029± 

 3- 701 ± 

 3- 84i± 



S- 289 ± 



5-i77± 

 S- 230± 



6. S58± 

 6.382± 

 6.463± 



7-698± 



7-3l4± 

 7- 470± 



8. 278± 



7. 866± 



8. 049 ± 



8. I09± 



8.37I± 

 8. 26o± 



8.698± 

 8. 434± 

 8. S56± 



8.683± 

 8. 773 ± 

 8. 738± 



8. 367± 

 7- 889 ± 

 8. iii± 



8. 790 ± 



8. 205± 

 8.4S7± 



9. 036± 

 8. 6i6± 

 8. 750± 



7-932± 



7. 972± 

 7- 9SO± 



I. 500±i 



7. 776± 



8. I3i± 



8. 500±i 

 7. 500± 

 7.875± 



16.489 



Standard de- 

 viation (in 

 gallons). 



2. 4oo±o, 

 2. s69± 

 2. 5i4± 



2. 392± 

 2. 480 ± 

 2. 449± 



2- 734± 

 2. 7Soi: 



2- 743± 



2. 798 ± 

 2. 7I5± 

 2. 7SS± 



2. 933± 

 2. 972± 

 2. 962± 



3-079± 



2. 877± 

 2. 97o± 



2. 984± 

 2. 9S2± 

 2. 969 ± 



2. 9II± 

 2. 901 ± 



2. 909± 



5. 049± 



3- 030± 

 3'037± 



3- 593 ± 

 3059± 

 3-330± 



3- 143 ± 



3-025± 

 3 o87± 



2-99S± 



2. 968± 

 2.986± 



3-S09± 

 3- 795 ± 



3. 640 ± 



3- 747±I 

 3. 046± 

 3.3o6± 



2. 24S± 



2. 389± 

 2. 364± 



Coefficient of 

 variation. 



7. 26o±i. 432 

 9- l65±i.326 

 8.47i± .980 



7-053± 

 8. io3± 

 7- 690± 



7- 88s± 

 8. ii8± 



8. 0I2± 



337 

 310 

 229 



384 

 367 

 266 



:6. 899± . 572 



6. S7S± -368 



16. 736± . 272 



6. 575± .449 



7. I63± .385 

 i6.95S± -294 



[6. S46± . 464 



6. 103 ± .397 



6. 4s6± .322 



6. 477± .491 



6. 07I±; .410 



6. 2s8± .315 



5. 566± . S23 



5. 739± .489 



5-675± -358 



6.3i8± 

 6. I38± 



6. 2io:i: 



9- 56o± 



7. IOI± 

 8. 384± 



712 

 566 



444 



638 



6. 726±I. 160 

 6. 6i7±i.oo2 

 6. 723 ± . 761 



5. 773 ±1-682 

 S.943±I-2l8 

 S.924± -989 



19. s66±2. 06s 

 21. ii6±2. 477 



20. 28o±i. S91 



17- 429 ±6. 053 



17. I38±i.929 



18. 234±i. 958 



12. I37±4-IS3 

 13- 653 ±2. 707 

 13- 22S±2. 269 



17. 081 



