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Posted 8/22/2014

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ALEXANDRIA, VIRGINIA.  The Waterborne Commerce Statistics Center (WCSC) provides data to the public concerning waterborne commerce taking place on navigational channels of the U.S.  One product, among many, has been the provision of commodity specific indicators for monthly tonnage moving along the inland waterway system.

The data is collected, processed, and released from two sources: the Lock Performance Monitoring System (LPMS) and Waterborne Commerce (WBC) data. The LPMS data is a report of commodities moving through inland locks and is typically available within a month.  The WBC data is developed from monthly reports furnished by operators moving the commerce and requires a great deal of processing and time in order to release the products.

Due to the delay in WBC release, indicators are released for the WBC inland waterway data via the WCSC website.  Essentially, this is an estimation of WBC tonnage based on the tonnage reported through the LPMS.  The indicators are estimated using linear regression models that mathematically delineate the relationship between the tonnages reported for a given month at key LPMS locks to the monthly WBC value.  These relationships are used to “nowcast” the WBC data.

Indicator models were developed for Total commodities, Coal, Farm & Food, Chemical, and Petroleum.  These models were developed using an iterative approach, reviewing key outputs at each step, refining, and then re-estimating until final models were achieved.  The statistical program STATA was used to automate the approach.  This program allowed for regressions to be generated and reviewed of all possible models of single lock, dual lock, lag, monthly dummies, etc.  Generating models this way using STATA was instrumental in identifying key locks and models with the best fit for each commodity group.

Additional information regarding the indicator development can be obtained from Amy Tujague at 504-862-1441.

Learn More

Models can be found here: http://www.navigationdatacenter.us/wcsc/monthlyindicators.htm

For more information, visit www.iwr.usace.army.mil