2 N. n. Experiment Station 



A certain amount of variation is to be expected in com- 

 paring the results of two or more purity analyses. For 

 this reason a "tolerance" or difference is allowed between 

 the average results of our tests and the guarantee in 

 accordance with the following formula. The sample is 

 considered as being made up of two parts, the one being 

 the pure seed and the other the balance of the sample. 

 The tolerance in per cent allowed for the larger part or 

 pure seed is two-tenths of one per cent plus 20 per cent 

 of the lesser part. For instance, if a sample is guaranteed 

 99.60 per cent pure seed, it may test as low as 99.32 per 

 cent or as high as 99.88 per cent and w^ould be "satisfac- 

 tory". In the same way, a sample guaranteed 92.80 per 

 cent may test as low as 91.17 per cent or as high as 94.43 

 per cent and be "satisfactory". If a sample is found to 

 be better than the highest figure in the tolerance, it is 

 marked "Above" in this bulletin; if lower than the lowest 

 figure, the actual figure is reported. 



A wider tolerance for germination than for purity is 

 allowed between the results of the test and the gurantee, 

 as follows: 



Guarantee Allowable variation 



per cent per cent 



90 or over 6 



80 or over but less than 90 7 



70 or over but less than 80 8 



60 or over but less than 70 9 



Less than 60 10 



Accordingly, a sample guaranteed 92 per cent germina- 

 tion is ' ' satisfactory " if it tests 86 per cent to 98 per cent. 

 A sample guaranteed 85 per cent may fall as low as 78 

 per cent or as high as 92 per cent. If a sample tests higher 

 than the per cent of variation allowed it is marked 

 "Above" in this bulletin or, if it tests below the varia- 

 tion allowed, the actual figure is reported. 



