In this paper, we present an initial exploration of the use of ship movements around the UK. Two new monthly shipping indicators have been derived from Automatic Identification System (AIS) data, the international system for tracking ship movements:
- ‘Time-in-port’ is based on aggregate time spent by ships in 10 major UK ports.
- ‘Total traffic’ is based on the number of unique ships entering the 10 major UK ports.
These indicators are likely to be important in supplementing our understanding of international trade activity. They offer a fast indication of the level of shipping activity, which is, as we show, related to trade in goods, by individual port.
We compare data for July 2016 to August 2018 to official statistics for gross value added (GVA) and trade statistics. We find a surprisingly good correlation between the shipping indicators and imports, particularly given the noisy nature of these variables. However, care must be taken in the interpretation. We do not have a sufficiently long time series to be able to seasonally adjust it, so correlations may be driven largely by seasonal variation. Furthermore, although the overall correlation is reasonably good, individual points can deviate strongly. For these reasons, we do not recommend using these indicators on their own as predictors of GDP or other headline economic statistics.
The relationships between time in port and international trade in goods could potentially be used in a mathematical model in combination with other indicators to estimate trends in trade. Given the fact that AIS can be obtained in timely fashion, in fact in near real time, the output of such a model can be a valuable tool for early economic trend discovery.
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