

WEIGHT VARIATION OF PACKAGE FOODS. iy, 
TABLE 12.—Effect of speed on accuracy of machines. 






Fatale 
iation 
es Average ON 
= Make of : Average S ofsingle 
Experiment No. machines weight. | “DUS | packages Speed. Product. 
aim. f 
rom 
average. 
Pkgs. per 
Ozs. Ozs. Oz. Oz. hour. 
3 SAU EE SEE ee Bee 1 16.09 16.21 0.12 0.029 450 | Ground coffee. 
SAO Oe BCE CoS cere eee 1 16.09 16.21 -12 -059 679 Do. 
Des RISE ORO ees 1 16.09 16.09 -00 . 028 783 Do. 
ISH ER oc 0 GA ey See ae a ; .08 . 039 637 
Average deviation from 0 average—aim..................... - 080 
SS SC ade ee ae | 2 16.13 16.12 —.01 076 1,860 | Whole coffee. 
See eyo eats Sistererctjars acl | 2 16.13 16.33 - 20 - 106 2,580 Do. 
INS Reg Ds Se RS nc a Re Oe ote Pe preragm  e ea 10 | .091 2,220 
Average deviation from 0 average—aim...:................- -105 | 
Soap aOES op CEO 3 16.01 15.93 —.08 052 706 Do 
Bosman ae heer 3 16.01 15.98 —.03 045 1,241 Do 
SEAS AOU BO OR COR Ores | 3 16.01 16.02 -01 048 1,274 Do 
SSS See ae ees 3 16.01 15.95 —.06 059 1,440 Do 
erases sete = RS eR ue IRV apa ra Tawi cae ce 
Average deviation from 0 average—aim....................- 045 
Seo ARE OOO eee 6 16.00 16.06 -06 - 063 409 Do. 
Siete eee een cine aint Sere 6 16.00 15.99 —.01 057 818 Do 
ee ters EI 6 16.00 16.00 00 063 1,333 Do 
ANSEF STS See ek EG re a .| .02 .061 853 
Average deviation from 0 average—aim........-..-......... 023 
SSG Normne arses eare ite eee Ct 8 12.15 12.10 —.05 -050 430 | Cocoa. 
S5 OVE sana nese 8 1215 12.13 —.02 121 514 Do. 
PAV CTE peer te ren See a AE EES Ree atl 5 —.03 085 472 
Average deviation from eee Pee iseaer ere eee 035 

The relation of speed to accuracy is shown graphically in Figure 1. 
It will be noted that in every case the accuracy increases as the speed 
decreases. Consequently large variations may be introduced by 
packing too fast, and, conversely, lower speeds tend to produce 
smaller variations. 
Calculations have been made and data collected which show that 
variations of 0.106 ounce on the average of 50 packages and 0.213 
ounce on single 1-pound packages are approximately the limiting 
variations of good commercial practice by hand weighing. Com- 
putations based on the figures in Table 12 show that when the pack- 
ages are packed by the various machines the chances of occurrence 
of variations greater than 0.106 and 0.213 ounce are as given in 
Table 13. 
Since to meet the practical limits of a normal frequency distribu- 
tion the variation must be of such magnitude that the chances thus 
calculated should be at least 1 in 1,000, the figures in Table 13 do not 
indicate that machines weigh as well as hand weighers. All these 
machines, however, were set by the operator’s own method, which 
consisted in testing four or five individual packages. Such a pro- 
cedure is based upon the assumption that each package is very near 
the average, when, as a matter of fact, wide variation occurs, and 
erroneous settings result. A more accurate setting would be obtained 
