PRECISION Sample Clauses

PRECISION. From time to time COUNTY may submit to CONTRACTOR, without prior notification or identification as such, two or more samples of identical composition, or differing in composition by a known factor established by volumetric dilution. Unsatisfactory replicate analyses, as defined in Paragraph D, below, may be cause for cancellation of this contract by COUNTY, and/or for penalty discounts of CONTRACTOR’s invoices, in accordance with the provisions of that paragraph.
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PRECISION. The precision studies were performed using three lots of Cascade Abrazo PT-C Level 1 and Level 2 controls and one lot of Cascade Abrazo PT-C cards. The studies were performed by multi non-laboratorian operators (POC) at three sites across 6 Cascade Abrazo analyzers. Each operator performed 2 runs per day, 2 tests per run on each lot of Abrazo PT-C test controls over a period of 20 days. Within-run Precision* N= 80 Lot to Lot Precision* N= 80 Operator to Operator Precision* N= 80 *Precision studies were performed according to EP5-A2.6 REFERENCES RÉFÉRENCES/LITERATUR/RIFERIMENTI/REFERENCIAS
PRECISION. Within Run: A normal and an abnormal control were run alternately on a single gel with the following results: Normal Control (n = 34) Protein Fraction Mean % SD CV Albumin 53.7 0.8 1.5% Alpha1 4.0 0.2 4.3% Alpha2 9.8 0.3 2.8% Beta 16.9 0.2 1.4% Gamma 15.6 0.5 2.9% Abnormal Control (n = 33) Protein Fraction Mean % SD CV Albumin 47.3 0.8 1.6% Alpha1 3.5 0.1 3.6% Alpha2 9.0 0.2 2.7% Beta 13.0 0.2 1.8% Gamma 27.2 0.4 1.4% Between-Run: A normal and an abnormal control were run alternately on nine gels with the following results: Normal Control (n = 304) Protein Fraction Mean % SD CV Albumin 54.4 1.1 2.0% Alpha1 3.9 0.2 6.0% Alpha2 9.6 0.3 3.6% Beta 16.6 0.4 2.7% Gamma 15.5 0.5 3.4% Abnormal Control (n = 292) Protein Fraction Mean % SD CV Albumin 47.7 0.8 1.8% Alpha1 3.5 0.2 5.1% Alpha2 8.9 0.3 2.8% Beta 12.8 0.3 2.3% Gamma 27.1 0.4 1.5% CORRELATION Normal and abnormal specimens were analyzed using the SPIFE Split Beta SPE system and the SPIFE Touch Split Beta SPE system. n = 30 Y = 1.0043X - 0.083 R = 0.9999 X = SPIFE Split Beta SPE Y = SPIFE Touch Split Beta SPE BIBLIOGRAPHY
PRECISION. The movable measurement platform (satellite site shelter) was periodically deployed at the core site for collocated measurements with the results summarized in Table 3-2. These metrics are based on all data. Including only those concentration values exceeding ten times the MDL reported in Table 3-1 yields collocated precision of 1.0 μg/m3 (4.6%) for PM1.0 (N = 3) and 2.0 μg/m3 (9.5%) for PM2.5 (N = 10). All concentration values were greater than ten times the MDL for the collocated PM10 data set. In addition to the completely independent measurements, two PM2.5 samples were collected in parallel on most days. The last row of Table 3-2 shows the collated precision for those measurements which shared the same pump and timer but had independent flow control elements. This measurement captures a subset of the overall collocated variability. Bias and Comparability. One quality check for the PM gravimetric mass data is to test whether PM1.0 < PM2.5 < PM10 mass within the measurement uncertainty. Figure 3-1 shows scatter plots for PM1.0 and PM2.5 (Fig. 3-1a), and PM2.5 and PM10 mass (Fig. 3-1b). There were four cases where PM1.0 exceeded PM2.5 (by 0.5, 0.7, 0.8, and 1.0 μg/m3), and one case where PM2.5 exceeded PM10 (by 0.2 μg/m3). Assuming the 0.5 μg/m3 absolute precision estimated from PM2.5 samplers from the same sampling system (last row of Figure 3-2), these cases can be explained by measurement error. In addition to the above Supersite platform measurements, the Illinois EPA (IEPA) operated a full suite of NAAQS compliance monitors, including a PM2.5 FRM, at the 13th & Tudor (East St. Louis) at the monitoring site which shared the same physical footprint as the Supersite. The IEPA and Supersite PM2.5 gravimetric mass measurements were independently conducted at all levels (different field staff, audit devices, handling and storage facilities, and gravimetric mass analytical laboratories). IEPA samplers and continuous analyzers were included in the systems and performance audits conducted by DRI. Comparability between the IEPA FRM and Supersite Harvard Impactor (HI) gravimetric mass measurements are shown in Figure 3-2a for the period 4/14/01 through 3/31/2003 and excluding one value at (95.7, 88.8). A reduced major axis regression yielded: IEPA FRM = (0.92 ± 0.05)× HI + (−0.8 ± 0.7 μg / m3 ) The FRM and HI measurements are comparable with the HI biased high. This bias likely arises from differences in samplers, including but not limited to the impactor cutp...
PRECISION. Collocated precision results for units #121 and #123 are summarized in Table 3-3. A portion of this dispersion is due to a bias between the instruments. Transforming the hourly data for #123 using a constrained linear least squares regression of #123 on #121 (slope 0.881) yields a collocated precision of 2.9 μg/m3 (13.0%).
PRECISION. Precision estimates for PILS-IC, based on both propagation of precision for the intrinsic measured parameters and from collocated measurements, have been reported elsewhere (Xxxxxx et al. 2003). In contrast to that relatively short duration study with stable operating conditions, the East St. Louis deployment focused on sustained, routine measurements during which additional sources of imprecision can surface. Numerous factors influencing PILS-IC measurement precision are described by Xxxxxxxxxxx (2005; Chapter 5), which focused on a newer-generation version of PILS compared to the version deployed for the 2001-2002 measurement program. We have not fully assessed how the factors identified by Xxxxxxxxxxx (2005) affect the quantitative precision estimates for the earlier generation measurements and rely upon bias and comparability metrics to document the data quality.
PRECISION. Bae et al. (2004) present the methodology used to estimate the sample-specific precision based on a propagation of uncertainties for the chemical analysis (as reported by the laboratory Sunset OCEC analyzer) and the field blank correction. For concentration values exceeding ten times the MDL, the precision based on the reported uncertainties was 9.4% C.V. for OC (N = 369) and 12.8 % C.V. for EC (N = 25). The EC precision modestly exceeds the 10% DQO, and it is noted that less than 6% of the samples exceeded ten times the estimated MDL. Collocated carbon sampling was not formally programmed. Eleven collocated samples were collected in 2001, however, with the results presented in Table 4-3 for samples exceeding ten times the above MDL values. Note the EC precision estimate is not robust because it is based on only one sample pair. Table 4-3. Collocated 24-hour integrated PM2.5 carbon measurements.(a) Parameter Method Collocated N and N (Conc > 10×MDL) Absolute Precision (μg/m3) Mean Conc. (μg/m3) Relative Precision TC UWM / ACE-ASIA 11 (7) 0.31 4.09 7.5 % OC UWM / ACE-ASIA 11 (9) 0.36 3.06 11.9 % EC UWM / ACE-ASIA 11 (1) 0.40 1.83 22.0 %
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PRECISION. Collocated data was collected and analyzed for the period 4/11/01-6/30/01. To remove the loading-dependent artifact from the collocated instrument comparisons, the data was censored to retain only those 5-minute records with attenuation difference less than 5 units between the instruments. Furthermore, only those records with arithmetic mean concentration greater than ten times the MDL were retained, where the MDL value is assumed to be 0.050 μg/m3 and is based on three times the standard deviation of dynamic blank measurements. The results are summarized in Table 4-4. There is an improvement in the collocated precision when the data is censored to include only those records with similar attenuation for both instruments; with a four-fold worse precision when including all data. The difference between these two collocated precision values demonstrates the error introduced by the loading-dependent effect, and will typically vary by location and time of year. While it should be not be interpreted as a representative measurement error, it will be present in the data unless appropriate methodologies are used to compensate for the loading effect. For this reason, record-specific attenuation (ATN) values have been reported along with the mass concentration values for the data set submitted to the NARSTO database. Table 4-4. Collocated 5-minute PM2.5 Aethalometer BC measurements. Parameter Method Collocated N Absolute Precision (μg/m3) Mean Conc. (μg/m3) Relative Precision BC(a,b) Xxxxxxxx XX-16 15,338 0.313 1.232 25.4 % BC(a,c) Xxxxxxxx XX-16 1,042 0.249 1.353 18.4 %
PRECISION. In 2006 a subset of samples were reanalyzed by DRI using a newly-commissioned XRF instrument which replaced the XRF instrument used for the first two years of St. Louis – Midwest Supersite samples. This analysis provides a stringent test for the analysis methods contribution to collocated precision since different instruments were used. The last four columns of Table 4-5 report the comparisons for samples with the first analysis concentration at least ten times the DRI-reported MDL. Twenty-three of the forty reported elements had no concentration values exceed this threshold. Relative precision was better than 10% for all elements with at least five concentration values above the threshold. Table 4-5. XRF analysis Minimum Detection Limit (MDL) and Instrument Detection Limit (IDL) estimates, and replicate analysis of the same filter samples by a different XRF instrument than used for the St. Louis – Midwest Supersite samples. Element MDLa (μg/m3) IDLb (μg/m3) MDLc (μg/m3) Replicate Analysis (All Data) Replicate Analysis (Conc>10xMDL) N Conc (μg/m3) Prec (μg/m3) Rel Prec N Conc (μg/m3) Prec (μg/m3) Rel Prec Sodium (Na) 0.0385 0.4063 0.4154 26 0.1461 0.1217 83% 0 Magnesium (Mg) 0.0140 0.0523 0.0819 26 0.0316 0.0261 82% 0 Aluminum (Al) 0.0056 0.0238 0.0289 26 0.0431 0.0167 39% 0 Silicon (Si) 0.0035 0.0463 0.0248 26 0.0992 0.0080 8% 22 0.1127 0.0083 7.3% Phosphorus (P) 0.0031 0.0075 0.0065 26 0.0487 0.0508 104% 1 0.3275 0.0831 25.4% Sulfur (S) 0.0028 0.0069 0.0444 26 1.4216 0.0985 7% 26 1.4216 0.0985 6.9% Chlorine (Cl) 0.0056 0.0061 0.0040 26 0.0233 0.0399 171% 4 0.0889 0.0996 112.0% Patassium (K) 0.0034 0.0044 0.0039 26 0.0666 0.0029 4% 26 0.0666 0.0029 4.4% Calcium (Ca) 0.0026 0.0083 0.0055 26 0.1102 0.0030 3% 25 0.1141 0.0031 2.7% Titanium (Ti) 0.0016 0.0010 < 0.0001 26 0.0034 0.0022 63% 0 Vanadium (V) 0.0014 < 0.0001 < 0.0001 26 0.0009 0.0011 113% 0 Chromium (Cr) 0.0010 0.0003 0.0008 26 0.0007 0.0005 66% 1 0.0089 0.0008 9.3% Manganese (Mn) 0.0009 0.0010 0.0002 26 0.0050 0.0012 25% 6 0.0132 0.0012 9.2% Iron (Fe) 0.0008 0.0002 0.0071 26 0.1163 0.0106 9% 26 0.1163 0.0106 9.1% Cobalt (Co) 0.0005 0.0005 0.0006 26 0.0005 0.0009 172% 0 Xxxxxx (Ni) 0.0005 0.0002 0.0002 26 0.0003 0.0004 130% 0 Copper (Cu) 0.0006 0.0002 0.0015 26 0.0543 0.0052 10% 19 0.0737 0.0060 8.2% Zinc (Zn) 0.0006 0.0020 0.0040 26 0.0405 0.0015 4% 26 0.0405 0.0015 3.8% Gallium (Ga) 0.0010 0.0031 0.0015 26 0.0005 0.0008 168% 0 Arsenic (As) 0.0009 0.0001 0.0008 26 0.0029 0.0018 64% 0 Selenium (Se)...
PRECISION. Do the data have an acceptable margin of error? Yes No Comments ⮚ Is the margin of error less than the expected change being measured? ❑ ❑ ⮚ Is the margin of error is acceptable given the likely management decisions to be affected? (Consider the consequences of the program or policy decisions based on the data) ❑ ❑ ⮚ Have targets been set for the acceptable margin of error? ❑ ❑ ⮚ Has the margin of error been reported along with the data? ❑ ❑ ⮚ Would an increase in the degree of accuracy be more costly than the increased value of the information? ❑ ❑ Recommendations for improvement:
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