@article{ref1,
title="Testing for instrumentation in transportation time series data: a case study",
journal="Transportation research record",
year="1997",
author="Rock, Steven",
volume="1581",
number="",
pages="89-92",
abstract="Instrumentation is one of the threats to the validity of experiments. Four possible cases of instrumentation in a time series of traffic accident statistics in Illinois since the mid-1970s were tested, primarily by using autoregressive integrated moving average methods. Two of these cases, a 1977 change in the reporting threshold for property-damage-only (PDO) accidents and a 1989 change in the definition of a fatality, were not found to be significant. A 1989 change in the method of tabulating monthly data and a 1992 change in the reporting threshold for PDO accidents were statistically significant. These two cases combined could account for a more than 15 percent decline in PDO accidents.<p /><p>Language: en</p>",
language="en",
issn="0361-1981",
doi="10.3141/1581-12",
url="http://dx.doi.org/10.3141/1581-12"
}