Table 1.

USEPA criteria for characterizing data quality level (adapted from US EPA 1998)

Data quality level	Statistical parameter
Definitive level	r 2 = 0.85–1.0 RSD on replicate measurements ≤10 % Inferential statistics indicate the two data sets are statistically similar (test for regression slope = 1 and intercept = 0 at the 0.05 level).
Quantitative screening level	r 2 = 0.70–1.0 RSD ≤20 % Inferential statistics indicate the two data sets are statistically different.
Qualitative screening	r 2 < 0.70 RSD >20 % Data has less than 10 % false negative rate.