An elaborated pattern-based method of identifying data oscillations from mobile device location data
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In recent years, passively collected GPS data have been popularly applied in various transportation studies, such as highway performance monitoring, travel behavior analysis, and travel demand estimation. Despite multiple advantages, one of the issues is data oscillations (aka outliers or data jumps), which are unneglectable since they may distort mobility patterns and lead to wrongly or biased conclusions. For transportation studies driven by GPS data, assuring the data quality by removing noises caused by data oscillations is undoubtedly important. Most GPS-based studies simply remove oscillations by checking the high speed. However, this method can mistakenly identify normal points as oscillations. Some other studies specifically discuss the removal of outliers in GPS data, but they all have limitations and do not fit passively collected GPS data. Many studies are well developed for addressing the ping-pong phenomenon in cellular data, or cellular tower data, but the oscillations in passively collected GPS data are very different for having much more various and complicated patterns and being more uncertain. Current methods are insufficient and inapplicable to passively collected GPS data. This paper aims to address the oscillated points in passively collected GPS data. A set of heuristics are proposed by identifying the abnormal movement patterns of oscillations. The proposed heuristics well fit the features of passively collected GPS data and are adaptable to studies of different scales, which are also computationally cost-effective in comparison to current methods.
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