There has been very little research in the area of air cargo demand analysis and
forecasting. This thesis attempts to investigate the application of gravity models to air
cargo. Using international export volumes from Vancouver International Airport in 1998,
a gravity model was built. The inclusion of tariffs as an impedance factor allowed testing
of the effect of tariffs as predicted by gravity models. The results were consistent with
international trade theory that tariffs provide a barrier to international trade. Further, a
comparison is made between aggregate and disaggregate models (across commodities).
It was found that aggregation eliminates commodity specific characteristics.
In using the gravity model, there are two adjustments which need to be made to reduce
the bias in the model: firstly, adjustment is necessary to the bias inherent in the constant
term of a log-linear model; and a further adjustment is required when forecasting actual
levels rather than log levels. Even after adjustments for both types of bias, the gravity
model did not produce accurate forecasts. The aggregate model produced better forecasts
than the disaggregate model, but both sets of forecasts did not accurately predict the
actual volumes transported. This could be as a result of the stable nature of the variables
included in the model, which tend to change very slowly over time. Further, it is
apparent that other additional explanatory variables should be included in the models to
better capture the short-term changes in air cargo.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/12234 |
| Date | 05 1900 |
| Creators | Turner, Sheelah Anne |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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