Geography Reference
In-Depth Information
Fig. 7 a Percentage of completeness of temporal events by travel days. b Percentage of
completeness of temporal events by first and last stops of overnight trips. c Spatial-temporal data
accuracy levels by morning and afternoon stops
each overnight stay resets the clock and coherence across a day rolls through to
coherence across the itinerary. Figure
7
b shows the completeness with respect to
the first stop and the last stop of the morning-to-night trips. Both the first stop and
the last stop of these trips are close to temporal boundaries, therefore, both should
have better completeness of recording temporal events. Because last stops of the
day normally the overnight stop and their durations were recorded as description
''overnight'' instead of absolute values, thus the durations of the last stops are
highly completed, but in an uninformative way.
Figure
7
c illustrates variations in data quality within the day, dividing records
into morning and afternoon periods and looking in more detail at possible error
levels. Morning observations appear to provide higher quality data in general but
also suffer most from missing values for duration. The afternoon sees higher levels
of suspicious arrival times, an effect which translates into a considerable difference
in share of cases classified as a likely missing stop. Overall, the accuracy of
recorded data is higher in the morning, although not by much, while possible
omissions are far more prevalent as the day progresses.
