(d)Calculation of mean concentrations - (1)Reference method outlier test. For each of the measurement sets for each test site, check each reference method measurement to see if it might be an anomalous value (outlier) as follows, where Ri,j is the measurement of reference method sampler i on test day j. In the event that one of the reference method measurements is missing or invalid due to a specific, positively-identified physical cause (e.g., sampler malfunction, operator error, accidental damage to the filter, etc.; see paragraph (c)(2) of this section), then substitute zero for the missing measurement, for the purposes of this outlier test only.(i) Calculate the quantities 2 * R1,j/(R1,j + R2,j) and 2 * R1,j/(R1,j + R3,j). If both quantities fall outside of the interval, (0.93, 1.07), then R1,j is an outlier.(ii) Calculate the quantities 2 * R2,j/(R2,j + R1,j) and 2 * R2,j/(R2,j + R3,j). If both quantities fall outside of the interval, (0.93, 1.07), then R2,j is an outlier.(iii) Calculate the quantities 2 * R3,j/(R3,j + R1,j) and 2 * R3,j/(R3,j + R2,j). If both quantities fall outside of the interval, (0.93, 1.07), then R3,j is an outlier.(iv) If this test indicates that one of the reference method measurements in the measurement set is an outlier, the outlier measurement shall be eliminated from the measurement set, and the other two measurements considered valid. If the test indicates that more than one reference method measurement in the measurement set is an outlier, the entire measurement set (both reference and candidate method measurements) shall be excluded from further data analysis for the tests of this section.(2) For each of the measurement sets for each test site, calculate the mean concentration for the reference method measurements, using equation 11 of this section: View Image
Where:
Rj = The mean concentration measured by the reference method for the measurement set;
Ri,j = The measurement of reference method sampler i on test day j; and
n = The number of valid reference method measurements in the measurement set (normally 3).
(3) Any measurement set for which Rj does not fall in the acceptable concentration range specified in table C-4 of this subpart is not valid, and the entire measurement set (both reference and candidate method measurements) must be eliminated from further data analysis.(4) For each of the valid measurement sets at each test site, calculate the mean concentration for the candidate method measurements, using equation 12 of this section. (The outlier test in paragraph (d)(1) of this section shall not be applied to the candidate method measurements.) View Image
Where:
Cj = The mean concentration measured by the candidate method for the measurement set;
Ci,j = The measurement of the candidate method sampler or analyzer i on test day j; and
m = The number of valid candidate method measurements in the measurement set (normally 3).