The optical fractionator method determines the number of cells by multiplying the number of objects identified inside each counting box by the values of three ratios: a) the ratio between the number of sections sampled and the total number of sections (section sampling fraction
, ssf); b) the ratio of the counting box and the area of the grid (area sampling fraction
, asf); and c) the ratio between the height of the counting frame and the section thickness after histological procedures (thickness sampling fraction
The results of 20% bulk sampling confirmed that as bigger would be the bulk sampling fraction
with respect to the tonnage of material, more precise and accurate would be the results.
In order for this assumption to be met, it is necessary that the sampling fraction
(i.e., ratio of sample size to population size) be sufficiently small (Heckathorn, 2007).
For pyramidal cells: counting frame size (316 x 285[micro][m.sup.2]), section sampling fraction
(ssf, 1/4400 unit) and area sampling fraction
(asf, 1/44.4 unit) were determined.
The overall sampling fraction
for retail chicken meat-associated isolates was [approximately equal to] 60%, given that our primary hypothesis focused on retail chicken meat.