A simulation analysis to explore when using a calibration function is preferred over a scalar factor for calibrating safety performance functions

IF 2.4 3区 工程技术 Q3 TRANSPORTATION
M. Shirazi, Srinivas R. Geedipally
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引用次数: 1

Abstract

Abstract The Highway Safety Manual (HSM) recommends calibrating Safety Performance Functions using a scalar calibration factor. Recently, a few studies explored the merits of estimating a calibration function instead of a calibration factor. Although it seems a promising approach, it is not clear when a calibration function should be preferred over a scalar calibration factor. On the one hand estimating a scalar factor is easier than estimating a calibration function; on the other hand, the calibration results may improve using a calibration function. This study performs a simulation study to compare the two calibration strategies for different ranges of data characteristics (i.e.: sample mean and variance) as well as the sample size. A measure of prediction accuracy is used to compare the two methods. The results show that as the sample size increases, or variation of data decreases, the calibration function performs better than the scalar calibration factor. If the analyst can collect a sample of at least 150 locations, calibration function is recommended over the scalar factor. If the HSM recommendation of 30-50 locations is used and the analyst desires a better accuracy, calibration function is recommended only if the coefficient of variation of data is less than 2. Otherwise, calibration factor yields better results.
当使用校准函数优于标量因子来校准安全性能函数时,进行模拟分析以探索
摘要公路安全手册(HSM)推荐使用标量校准因子来校准安全性能函数。最近,一些研究探讨了估计校准函数而不是估计校准因子的优点。虽然这似乎是一种很有前途的方法,但尚不清楚何时应该优先使用校准函数而不是标量校准因子。一方面,估计标量因子比估计校准函数更容易;另一方面,使用校准函数可以改善校准结果。本研究进行了模拟研究,比较了两种校准策略在不同范围的数据特征(即:样本均值和方差)以及样本量。用一种预测精度度量来比较这两种方法。结果表明,随着样本量的增大或数据变化量的减小,该校正函数的校正效果优于标量校正因子。如果分析人员可以收集至少150个位置的样本,则建议在标量因子上使用校准功能。如果使用HSM推荐的30-50个位置,并且分析人员希望获得更好的精度,则只有当数据的变异系数小于2时,才建议使用校准函数。否则,校正因子可获得更好的结果。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
6.00
自引率
15.40%
发文量
38
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