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Chapter 1 | IntroductionRemoteness Classifications. Spatial information was incorporated in some datasets.This information is needed for geospatial analysis and mapping. Demographic datafrom the ABS Censuses were also merged (according to the ABS GeographicalClassification) to form some final datasets. Each dataset contains different set ofcross-sectional variables across time in the regional aviation industry. The data canbe analysed at airport level, by air route, by aircraft type and by airline. It can alsobe cross-classified by state and territory, AGSC Remoteness Classification, StatisticalLocal Area (SLA) and airport classification.Data quality issuesThe constructed database has an extensive coverage of the regional aviation market.However, there are some data quality issues that are worth noting:• Accuracy of the information is sometimes affected when erroneous data werecollected or reported.• Missing data between years could also cause misinterpretation in analyses. This isparticularly a concern when some zeros in the dataset represented genuine zerosand some were actually missing values.• Continuity of the time series was affected when data were collected in some yearsand not in others.One other data constraint was that information on revenue passengers was notreadily available by origin and destination (OD). OD data generally represents theactual scale of demand for air services reasonably well. A count of OD traffic depictsthe actual trip undertaken by the passenger irrespective of the number of flight stagesthat constitute the journey. Without the OD data, a reasonable proxy is needed.Basically, the ATS data collects and estimates the number of revenue passengersusing two approaches:• traffic on board by stage (TOB) measures the number of revenue passengers onboard for each flight stage• uplifts and discharges (UD) measures the number of revenue passengers withinthe same flight number between two ports not necessarily directly connected.Relative to TOB, UD provides a closer approximation of OD demand for air services(BTRE 2000). However, not all the airlines supply UD data so it was necessary to useTOB data. Thus it is important to note that, unless otherwise stated, all revenuepassenger data used in this study is based on TOB data and the number of regionalair routes estimated in this report is based on the number of flight stages. Figure1.2 shows differences in percent between the aggregated TOB and UD estimatesof revenue passengers carried on regional air routes over the past 22 years. TOBdata have been consistently higher than UD data but the difference has reduceddramatically over the years.13