The index incorporates container throughput data collected on an ongoing basis by the ISL Monthly Container Port Monitor at 94 international ports, which account for about 64 percent of global container throughput. The current quick estimate for the Container Throughput Index is based on data from about 64 percent of the throughput reflected in the index. Since international trade is mainly handled by ocean-going vessels, container throughputs allow reliable conclusions to be drawn about world trade. Because many ports report on their activities as early as two weeks after the end of a month, the RWI/ISL Container Throughput Index is a reliable early indicator of the development of international trade in processed goods and thus also of global economic activity. The container throughput index is part of the statistics on foreign trade in the „Dashboard Deutschland“ of the Federal Statistical Office.
Data series for individual ports are available in the ISL Monthly Container Port Monitor.
The Container Throughput Index is a joint project of RWI with the Institute of Shipping Economics and Logistics (ISL). It aims at providing timely information on short term trends in international trade. The index is based on the consideration that containers have become the most important means of transporting processed products. Therefore, the global container throughput and international trade can be expected to be highly correlated.
As a part of their monthly reporting many ports publish data on container throughput expressed in twenty foot equivalent units (TEU). ISL collects these data systematically in its port database. The 91 ports covered in the index account for about 6 out of 10 containers handled worldwide.
Calculating the indicator starts about 20 days after the end of each month. At that time, about 25 ports have already published information about the container throughput in the latest months, which allows for a flash estimate of the indicator. Data still missing are forecasted using statistical time series models. Thereafter, the data are added up and the sum is adjusted for seasonal and calendar effects. Furthermore, the trend-cycle component of the seasonally adjusted figures is estimated to eliminate irregular influences. One month later, as a rule data on 65 ports are available. Then an update of the figures already published is made and a new flash estimate for the latest month is released.
Hitherto, the RWI/ISL-Container Throughput Index shows a close correlation with world trade. The index provides valuable input into business cycles analyses, since it is available 3 to 4 months in advance of data on world trade published by international organizations, and one month in advance of the first estimates of world trade volumes.