Okla. Admin. Code § 252:515-9-53

Current through Vol. 41, No. 19, June 17, 2024

Section 252:515-9-53 - Statistical method performance standards

Any statistical method chosen shall comply with the following performance standards, as appropriate.

(1)Distribution of parameters. The statistical method used to evaluate groundwater monitoring data shall be appropriate for the distribution of chemical parameters or hazardous constituents.

(A) If the distribution of the chemical parameters or hazardous constituents is shown to be inappropriate for a normal theory test, then the data should be transformed or a distribution-free theory test should be used.

(B) If the distributions for the constituents differ, more than one statistical method may be needed.

(2)Type I error level. If an individual well comparison procedure is used to compare an individual compliance well constituent concentration with background constituent concentrations or a groundwater protection standard, the test shall be done at a Type I error level no less than 0.01 for each testing period.

(A) If a multiple comparisons procedure is used, the Type I experiment wise error rate for each testing period shall be no less than 0.05; however, the Type I error of no less than 0.01 for individual well comparisons must be maintained.

(B) This performance standard does not apply to tolerance intervals, prediction intervals, or control charts.

(3)Control chart approach.

(A) If a control chart approach is used to evaluate groundwater monitoring data, the specific type of control chart and its associated parameter values shall be protective of human health and the environment.

(B) The parameters shall be determined after considering the number of samples in the background data base, the data distribution, and the range of the concentration values for each constituent of concern.

(4)Tolerance or prediction interval.

(A) If a tolerance interval or a prediction interval is used to evaluate groundwater monitoring data, the levels of confidence and, for tolerance intervals, the percentage of the population that the interval must contain, shall be protective of human health and the environment.

(B) These parameters shall be determined after considering the number of samples in the background data base, the data distribution, and the range of the concentration values for each constituent of concern.

(5)Below detection limits.

(A) The statistical method shall account for data below the limit of detection with one or more statistical procedures that are protective of human health and the environment.

(B) Any practical quantitation limit that is used in the statistical method shall be the lowest concentration level that can be reliably achieved within specified limits of precision and accuracy during routine laboratory operating conditions that are available to the facility.

(6)Variability. If necessary, the statistical method shall include procedures to control or correct for seasonal and spatial variability as well as temporal correlation in the data.

Okla. Admin. Code § 252:515-9-53

Added at 20 Ok Reg 1151, eff 6-1-03