@article{frey_bammi_2003, title={Probabilistic nonroad mobile source emission factors}, volume={129}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0037331021&partnerID=MN8TOARS}, DOI={10.1061/(asce)0733-9372(2003)129:2(162)}, abstractNote={Quantitative methods for characterizing both variability and uncertainty are applied to case studies of nitrogen oxides (NOx) and total hydrocarbon air pollutant emission factors for construction, ...}, number={2}, journal={Journal of Environmental Engineering}, author={Frey, H. Christopher and Bammi, S.}, year={2003}, pages={162–168} }
 @article{frey_bammi_2002, title={Quantification of variability and uncertainty in lawn and garden equipment NOx and total hydrocarbon emission factors}, volume={52}, ISSN={["1047-3289"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036228881&partnerID=MN8TOARS}, DOI={10.1080/10473289.2002.10470792}, abstractNote={Abstract Variability refers to real differences in emissions among multiple emission sources at any given time or over time for any individual emission source. Variability in emissions can be attributed to variation in fuel or feedstock composition, ambient temperature, design, maintenance, or operation. Uncertainty refers to lack of knowledge regarding the true value of emissions. Sources of uncertainty include small sample sizes, bias or imprecision in measurements, nonrepresentativeness, or lack of data. Quantitative methods for characterizing both variability and uncertainty are demonstrated and applied to case studies of emission factors for lawn and garden (L&G) equipment engines. Variability was quantified using empirical and parametric distributions. Bootstrap simulation was used to characterize confidence intervals for the fitted distributions. The 95% confidence intervals for the mean grams per brake horsepower/hour (g/hp-hr) emission factors for two-stroke engine total hydrocarbon (THC) and NOx emissions were from -30 to +41% and from -45 to +75%, respectively. The confidence intervals for four-stroke engines were from -33 to +46% for THCs and from -27 to +35% for NOx. These quantitative measures of uncertainty convey information regarding the quality of the emission factors and serve as a basis for calculation of uncertainty in emission inventories (Els).}, number={4}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Frey, HC and Bammi, S}, year={2002}, month={Apr}, pages={435–448} }