Firstly, the representativeness of our population sample was assured by the recruitment strategy and the weighting scheme of the study, which took non-response and refusal to participate rates into account.
The main limitation of the study lies in the fact that at the regional level, while the representativeness of the sample is assured at the level of "all children aged 6 9," it is less reliable for the different sexes and age groups taken separately (in particular for the smaller regions).
The lack of noticeable heating of the samples was assured by determination of the Stokes/anti-Stokes ratio.
Quality of the RNA samples was assured with Bioanalyzer (Agilent Technologies) before downstream biotin-labeling and hybridization to the CodeLink Human Whole Genome Bioarray (GE Health care-Amersham Biosciences, Piscataway, NJ) following the manufacturer's manual.
The cDNA quality of all the examined samples was assured by GAPDH expression.
The homogeneity of the strip samples was assured by measuring the fractional area of tissue constituents with the point-counting method [ 3, 28, 29] using a 100-point grid with a known area (62,500 μm at 400× magnification) attached to the ocular of the microscope.
The homogeneity of the strip samples was assured by measuring the fractional area of the tissue constituents using the point-counting method [ 1, 34, 53] and a 100-point grid with a known area (62,500 μm at 400× magnification) attached to the ocular of the microscope.
Quantity measurement and the high quality of all mRNA samples were assured by analysis with the NanoDrop 1000, Agilent Bioanalyzer and the Agilent RNA 6000 Nano Kit (Agilent Technologies, Waldbronn, Germany).
With the new methods, the pre-analytical quality of tissue samples are assured and standardized before they are used for expensive molecular testing – an important consideration given the growing importance of assaying archival specimens for the suitability of new therapy.
