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When is Enough? Minimum Sample Sizes for On-Road Measurements of Car Emissions

机译：什么时候足够？

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摘要

The power of remote vehicle emission sensing stems from the big sample size obtained and its related statistical representativeness for the measured emission rates. But how many records are needed for a representative measurement and when does the information gain per record become insignificant? We use Monte Carlo simulations to determine the relationship between the sample size and the accuracy of the sample mean and variance. We take the example of NO emissions from diesel cars measured by remote emission monitors between 2011 and 2018 at various locations in Europe. We find that no more than 200 remote sensing records are sufficient to approximate the mean emission rate for Euro 4, 5, and 6a/b diesel cars with 80% certainty within a +/- 1 g NO per kg fuel tolerance margin (similar to +/- 50 mg NO per km). Between 300 and 800 remote sensing records are needed to approximate also the variance of the mean NO emission rates for those diesel car technologies. This translates to only 2 and up to 9 measurement days to characterize the means and their variance for a car fleet typical in Europe.
机译：远程车辆排放检测的能力源于所获得的大样本量及其对测得排放率的相关统计代表性。但是，代表性测量需要多少条记录，每条记录的信息增益何时变得微不足道？我们使用蒙特卡洛模拟来确定样本量与样本均值和方差的准确性之间的关系。我们以2011年至2018年期间在欧洲不同地点的远程排放监测仪测得的柴油车NO排放为例。我们发现，不超过200条遥感记录足以近似于欧洲4、5和6a / b柴油车的平均排放率，并具有80％的确定性，每公斤燃油容限范围为+/- 1 g NO（类似于每公里+/- 50 mg NO）。需要300至800个遥感记录来近似估算那些柴油车技术的平均NO排放率的方差。这意味着只有2个测量天，最多9个测量天，以表征欧洲典型汽车车队的均值及其变化。

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  • 来源
    《Environmental Science & Technology》 |2019年第22期|13284-13292|共9页
  • 作者

    Chen Yuche; Zhang Yunteng; Borken-Kleefeld Jens;

  • 作者单位

    Univ South Carolina Dept Civil & Environm Engn Columbia SC 29208 USA;

    Int Inst Appl Syst Anal A-2361 Laxenburg Austria;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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