Abstract
Aggregation of spatiotemporal data can encounter potential information loss or distort attributes via individual observation, which would influence modeling results and lead to an erroneous inference, named the ecological fallacy. Therefore, deciding spatial and temporal resolution is a fundamental consideration in a spatiotemporal analysis. The modifiable temporal unit problem (MTUP) occurs when using data that is temporally aggregated. While consideration of the spatial dimension has been increasingly studied, the counterpart, a temporal unit, is rarely considered, particularly in the traffic safety modeling field. The purpose of this research is to identify the MTUP effect in crash-frequency modeling using data with various temporal scales. A sensitivity analysis framework is adopted with four negative binomial regression models and four random effect negative binomial models having yearly, quarterly, monthly, and weekly temporal units. As the different temporal unit was applied, the result of the model estimation also changed in terms of the mean and significance of the parameter estimates. Increasing temporal correlation due to using the small temporal unit can be handled with the random effect models.
Highlights
Published: 31 May 2021Aggregation of spatiotemporal data allows researchers to save efforts in collecting data and modeling crash-frequency attributes efficiently
The decision of spatial and temporal resolution is a fundamental consideration in a spatiotemporal analysis
This research described the modifiable temporal unit problem (MTUP) effect in crash-frequency modeling using four dadatasets for the same study area, I-64 of Virginia, from 2011 to 2013, and in which the tasets for the same study area, I-64 of Virginia, from 2011 to 2013, inawhich crashand a crash data was aggregated by different temporal units: and a year, quarter,the a month, data was aggregated by different temporal a year, a quarter, a month, and a week
Summary
Aggregation of spatiotemporal data allows researchers to save efforts in collecting data and modeling crash-frequency attributes efficiently. Aggregating data can encounter potential information loss or distort attributes via individual observation, which would influence modeling results and lead to an erroneous inference, named the ecological fallacy. The decision of spatial and temporal resolution is a fundamental consideration in a spatiotemporal analysis. Much research has been conducted under the name of the modifiable area unit problem (MAUP). The MAUP stems from a zoning system used to collect geographical data and consider modifiable areal units in the analysis [1]. Corresponding to the MAUP, the modifiable temporal unit problem (MTUP) occurs when using data that is temporally aggregated. While consideration of the spatial dimension has been increasingly studied, the counterpart, the temporal unit, is rarely considered, in the traffic safety modeling field
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