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Implausible OECD motor vehicle travel data
Transportation Research Part D 79 (2020) 102246
Contents lists available at ScienceDirect
Transportation Research Part D journal homepage: www.elsevier.com/locate/trd
Implausible OECD motor vehicle travel data Leon S. Robertson
⁎
T
Yale University, Laboratory of Epidemiology and Public Health, 60 College Street, New Haven, CT 06510, United States
ARTICLE INFO
ABSTRACT
Keywords: OECD data Kilometers traveled CO2 emissions
To assess the fuel efficiency of motor vehicles in a given country, an estimate of kilometers traveled is required. Examination of kilometers per liter among countries contributing data to OECD revealed implausible results for several. Also kilometers per vehicle were anomalous. The kilometers per vehicle based on a stratified random sample of U.S. travel varied substantially from the numbers reported by OECD during 2000–2014. OECD motor vehicle travel data are unusable.
1. Introduction The integrity of science and the effective application of scientific data to practical problems depend on accuracy of data. A decade ago, the U.S. National Academy of Sciences issued a report that examined the accuracy of data from countries around the world regarding greenhouse gas emissions and said that data from Annex 1 countries (OECD, 2019a) in the United Nations Framework Convention on Climate Change was mostly accurate (Cicerone, et al., 2010). Among the most important sources of such emissions is CO2 from motor vehicles estimated at more than 20 percent of CO2 emissions (European Parliament, 2019). Recent research comparing the contiguous 48 U.S. states indicates that people drive, walk and use pedal cycles more on public roads as temperatures warm increasing road deaths as well as emissions from vehicles that further warm temperatures in an amplifying feedback system (Robertson, 2019). Such feedback contributes to acceleration of climate warming. In an attempt to replicate that study in other Organization for Economic Co-operation and Development (OECD) countries, I encountered issues of data validity from countries reporting data to OECD that precluded doing the study. To assess the possible effect of warming on CO2 emissions among geographic regions, it is necessary to control statistically for variation in fuel efficiency of vehicles among the regions. The purpose of this report is to alert scientists that the reported data on vehicle use in Annex 1 countries are unreliable. 2. Material and methods Since data are missing for several countries in OECD statistics after 2014, I compared kilometers per liter and kilometers driven per vehicle among countries for which data were reported by OECD during 2014 (OECD, 2019b). Noting a discrepancy between the U.S. government’s data on total miles driven per vehicle in the U.S. and the data on U.S. kilometers per vehicle from OECD, I transformed the U.S. data to kilometers and compared the trend in the two data series from 2000 through 2014. Consumption of gasoline and distillates were obtained from a website that provides economic data by country (TheGlobalEconomy.com, 2019). The use of diesel for transportation was estimated by subtracting heating oil from total distillates. Kilometers driven were obtained by multiplying the OECD report of kilometers per vehicle (OECD Statistics, 2019b) times the number ⁎
Address: 3217 Bermuda Village Drive, Bermuda Run, NC 27006, United States. E-mail address: [email protected].
https://doi.org/10.1016/j.trd.2020.102246
Available online 24 January 2020 1361-9209/ © 2020 Elsevier Ltd. All rights reserved.
Transportation Research Part D 79 (2020) 102246
L.S. Robertson
Fig. 1. Reported Kilometers per Estimated Liter by Country Using OECD data, 2014.
of vehicles registered in 2014. 3. Results Fig. 1 displays the estimated kilometers driven per liter of fuel among the included countries. The fuel efficiency indicator appears to be unusually low in the Slovak Republic, Latvia, Italy and France and near zero in Greece and Denmark. In contrast the numbers for the United Kingdom and the Netherlands are remarkably high. Miles per vehicle reported by OECD for calendar year 2014 are displayed in Fig. 2. Fifteen hundred or fewer kilometers per vehicle were reported for the Slovak Republic, Latvia, Italy, Greece, and Denmark. Two geographically small countries, Israel and Ireland, had the highest reported kilometers per vehicle. The trend in kilometers per vehicle in the U.S. according to U.S. Department of Transportation data and OECD are presented in Fig. 3. In the first years after the turn of the century, OECD reported higher kilometers per vehicle and a subsequent downward trend. By 2014, OECD was reporting 6 percent fewer kilometers per vehicle that the U.S. government’s reports.
Fig. 2. Reported Kilometers per Vehicle in OECD Data in 2014.
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Transportation Research Part D 79 (2020) 102246
L.S. Robertson
Fig. 3. U.S. Kilometers per Vehicle According to U.S. Highway Statistics and OECD, 2000–2014.
4. Discussion The low fuel efficiency derivable from OECD data from several countries is implausible. For example, kilometers traveled per liter of fuel near zero in Denmark are impossible given the fuel efficiency of new cars bought in Denmark. The lowest average in any given model year was 13.3 km/l in 1998 and has improved to more than 20 km/l (CEIC, 2020). At least part of the discrepancy is due to incredible data on kilometers driven per vehicle per year in several countries. The notes that accompany the data offer no explanation of how the data on kilometers traveled are collected with the exception of Italy that reported data for toll roads only. Most of the anomalous differences in the kilometers per vehicle date back to 2000, the first year in the OECD data. Numbers of vehicles registered and fuel use should be accurately reported because they are taxed. While tax avoidance could affect vehicle registration and fuel use data, it is unlikely that tax avoidance would distort the data enough to produce the results seen here. Certainly the discrepancy in the registered vehicle counts in the U.S. between OECD and the U.S. is not because of tax avoidance. Counting kilometers of travel is obviously problematic. The U.S. Federal Highway Administration (2019) uses a stratified random sample of traffic counts to estimate distances traveled. The state and national estimates are reported yearly (Federal Highway Administration, 2000–2014). Of course, OECD can only report the data that its member countries submit. In communications with an OECD statistician, I was told that OECD has no information on how the reporting countries estimate vehicle travel. In answer to a query as to where the U.S. data were obtained, the OECD statistician discovered that the U.S. Federal Highway Administration submitted data on vehicle registrations to OECD different from those that it published in Highway Statistics (Federal Highway Administration, 2000–2014). 5. Conclusion OECD travel data are unusable. Scientists should be alert to plausibility of data and wary of data of unknown provenance. Appendix A. Supplementary material Supplementary data to this article can be found online at https://doi.org/10.1016/j.trd.2020.102246. References CEIC, 2020, Denmark fuel efficiency: private car: new registration: households: Km per Litre. https://www.ceicdata.com/en/denmark/fuel-efficiency-new-registeredprivate-car/fuel-efficiency-private-car-new-registration-households-km-per-litre. Cicerone, R.J., et al., 2010. Verifying Greenhouse Gas Emissions: Methods to Support International Climate Agreements. National Academies Press, Washington DC.
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Transportation Research Part D 79 (2020) 102246
L.S. Robertson
European Parliament, 2019. CO2 emissions from cars: facts and figures (infographics). https://www.europarl.europa.eu/news/en/headlines/society/ 20190313STO31218/co2-emissions-from-cars-facts-and-figures-infographics. Federal Highway Administration, 2019. Highway Performance Monitoring System. https://www.fhwa.dot.gov/policyinformation/hpms/hpmsmanage.cfm. Federal Highway Administration, 2000-2014. Highway Statistics. https://www.fhwa.dot.gov/policyinformation/statistics.cfm. OECD, 2019a. List of Annex 1 Countries. http://www.oecd.org/env/cc/listofannexicountries.htm. OECD, 2019b. Road traffic in thousand vehicle-km per road motor vehicle. https://stats.oecd.org/. Robertson, L.S., 2019. Motor vehicle CO2 emissions in the U.S.: potential behavioral feedback and global warming. Weather, Climate Soc. 11, 623–628. TheGlobalEconomy.com, 2019. https://www.theglobaleconomy.com/.
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Contents lists available at ScienceDirect
Transportation Research Part D journal homepage: www.elsevier.com/locate/trd
Implausible OECD motor vehicle travel data Leon S. Robertson
⁎
T
Yale University, Laboratory of Epidemiology and Public Health, 60 College Street, New Haven, CT 06510, United States
ARTICLE INFO
ABSTRACT
Keywords: OECD data Kilometers traveled CO2 emissions
To assess the fuel efficiency of motor vehicles in a given country, an estimate of kilometers traveled is required. Examination of kilometers per liter among countries contributing data to OECD revealed implausible results for several. Also kilometers per vehicle were anomalous. The kilometers per vehicle based on a stratified random sample of U.S. travel varied substantially from the numbers reported by OECD during 2000–2014. OECD motor vehicle travel data are unusable.
1. Introduction The integrity of science and the effective application of scientific data to practical problems depend on accuracy of data. A decade ago, the U.S. National Academy of Sciences issued a report that examined the accuracy of data from countries around the world regarding greenhouse gas emissions and said that data from Annex 1 countries (OECD, 2019a) in the United Nations Framework Convention on Climate Change was mostly accurate (Cicerone, et al., 2010). Among the most important sources of such emissions is CO2 from motor vehicles estimated at more than 20 percent of CO2 emissions (European Parliament, 2019). Recent research comparing the contiguous 48 U.S. states indicates that people drive, walk and use pedal cycles more on public roads as temperatures warm increasing road deaths as well as emissions from vehicles that further warm temperatures in an amplifying feedback system (Robertson, 2019). Such feedback contributes to acceleration of climate warming. In an attempt to replicate that study in other Organization for Economic Co-operation and Development (OECD) countries, I encountered issues of data validity from countries reporting data to OECD that precluded doing the study. To assess the possible effect of warming on CO2 emissions among geographic regions, it is necessary to control statistically for variation in fuel efficiency of vehicles among the regions. The purpose of this report is to alert scientists that the reported data on vehicle use in Annex 1 countries are unreliable. 2. Material and methods Since data are missing for several countries in OECD statistics after 2014, I compared kilometers per liter and kilometers driven per vehicle among countries for which data were reported by OECD during 2014 (OECD, 2019b). Noting a discrepancy between the U.S. government’s data on total miles driven per vehicle in the U.S. and the data on U.S. kilometers per vehicle from OECD, I transformed the U.S. data to kilometers and compared the trend in the two data series from 2000 through 2014. Consumption of gasoline and distillates were obtained from a website that provides economic data by country (TheGlobalEconomy.com, 2019). The use of diesel for transportation was estimated by subtracting heating oil from total distillates. Kilometers driven were obtained by multiplying the OECD report of kilometers per vehicle (OECD Statistics, 2019b) times the number ⁎
Address: 3217 Bermuda Village Drive, Bermuda Run, NC 27006, United States. E-mail address: [email protected].
https://doi.org/10.1016/j.trd.2020.102246
Available online 24 January 2020 1361-9209/ © 2020 Elsevier Ltd. All rights reserved.
Transportation Research Part D 79 (2020) 102246
L.S. Robertson
Fig. 1. Reported Kilometers per Estimated Liter by Country Using OECD data, 2014.
of vehicles registered in 2014. 3. Results Fig. 1 displays the estimated kilometers driven per liter of fuel among the included countries. The fuel efficiency indicator appears to be unusually low in the Slovak Republic, Latvia, Italy and France and near zero in Greece and Denmark. In contrast the numbers for the United Kingdom and the Netherlands are remarkably high. Miles per vehicle reported by OECD for calendar year 2014 are displayed in Fig. 2. Fifteen hundred or fewer kilometers per vehicle were reported for the Slovak Republic, Latvia, Italy, Greece, and Denmark. Two geographically small countries, Israel and Ireland, had the highest reported kilometers per vehicle. The trend in kilometers per vehicle in the U.S. according to U.S. Department of Transportation data and OECD are presented in Fig. 3. In the first years after the turn of the century, OECD reported higher kilometers per vehicle and a subsequent downward trend. By 2014, OECD was reporting 6 percent fewer kilometers per vehicle that the U.S. government’s reports.
Fig. 2. Reported Kilometers per Vehicle in OECD Data in 2014.
2
Transportation Research Part D 79 (2020) 102246
L.S. Robertson
Fig. 3. U.S. Kilometers per Vehicle According to U.S. Highway Statistics and OECD, 2000–2014.
4. Discussion The low fuel efficiency derivable from OECD data from several countries is implausible. For example, kilometers traveled per liter of fuel near zero in Denmark are impossible given the fuel efficiency of new cars bought in Denmark. The lowest average in any given model year was 13.3 km/l in 1998 and has improved to more than 20 km/l (CEIC, 2020). At least part of the discrepancy is due to incredible data on kilometers driven per vehicle per year in several countries. The notes that accompany the data offer no explanation of how the data on kilometers traveled are collected with the exception of Italy that reported data for toll roads only. Most of the anomalous differences in the kilometers per vehicle date back to 2000, the first year in the OECD data. Numbers of vehicles registered and fuel use should be accurately reported because they are taxed. While tax avoidance could affect vehicle registration and fuel use data, it is unlikely that tax avoidance would distort the data enough to produce the results seen here. Certainly the discrepancy in the registered vehicle counts in the U.S. between OECD and the U.S. is not because of tax avoidance. Counting kilometers of travel is obviously problematic. The U.S. Federal Highway Administration (2019) uses a stratified random sample of traffic counts to estimate distances traveled. The state and national estimates are reported yearly (Federal Highway Administration, 2000–2014). Of course, OECD can only report the data that its member countries submit. In communications with an OECD statistician, I was told that OECD has no information on how the reporting countries estimate vehicle travel. In answer to a query as to where the U.S. data were obtained, the OECD statistician discovered that the U.S. Federal Highway Administration submitted data on vehicle registrations to OECD different from those that it published in Highway Statistics (Federal Highway Administration, 2000–2014). 5. Conclusion OECD travel data are unusable. Scientists should be alert to plausibility of data and wary of data of unknown provenance. Appendix A. Supplementary material Supplementary data to this article can be found online at https://doi.org/10.1016/j.trd.2020.102246. References CEIC, 2020, Denmark fuel efficiency: private car: new registration: households: Km per Litre. https://www.ceicdata.com/en/denmark/fuel-efficiency-new-registeredprivate-car/fuel-efficiency-private-car-new-registration-households-km-per-litre. Cicerone, R.J., et al., 2010. Verifying Greenhouse Gas Emissions: Methods to Support International Climate Agreements. National Academies Press, Washington DC.
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Transportation Research Part D 79 (2020) 102246
L.S. Robertson
European Parliament, 2019. CO2 emissions from cars: facts and figures (infographics). https://www.europarl.europa.eu/news/en/headlines/society/ 20190313STO31218/co2-emissions-from-cars-facts-and-figures-infographics. Federal Highway Administration, 2019. Highway Performance Monitoring System. https://www.fhwa.dot.gov/policyinformation/hpms/hpmsmanage.cfm. Federal Highway Administration, 2000-2014. Highway Statistics. https://www.fhwa.dot.gov/policyinformation/statistics.cfm. OECD, 2019a. List of Annex 1 Countries. http://www.oecd.org/env/cc/listofannexicountries.htm. OECD, 2019b. Road traffic in thousand vehicle-km per road motor vehicle. https://stats.oecd.org/. Robertson, L.S., 2019. Motor vehicle CO2 emissions in the U.S.: potential behavioral feedback and global warming. Weather, Climate Soc. 11, 623–628. TheGlobalEconomy.com, 2019. https://www.theglobaleconomy.com/.
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