This morning, the U.S. Energy Department reported domestic oil inventories rose for the seventh consecutive week. Playing catch-up with the government's figures, the industry-supported American Petroleum Institute had called for a 6.5-million-barrel jump, while sell-side analysts forecast a 1.6-million- to 2.0-million-barrel build. Actual crude oil inventories were reported to have risen by 1.4 million barrels.

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This week, the oil industry and Oil Patch watchers were all on the same side with their inventory guesses, but to vastly different degrees.

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Investors often use energy ETFs as proxies for the energy markets, but how well do these funds really track their underlying commodities?

• The problem with futures-based funds
• Why you can't use USO and UNG as direct proxies
• Does the 12-month solution work?

A .333 batting average may be top-drawer performance in baseball, but it's not so hot when prognosticating petroleum inventories. Ahead of the holiday-delayed government inventory report, the American Petroleum Institute released its estimates for crude oil, gasoline and distillate fuel supplies. When the government numbers were released this morning, only one of three API forecasts were on target.

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The national oil inventory report normally released by the U.S. Energy Information Administration on Wednesday morning will be delayed until Friday, Feb. 12 due to inclement weather. The EIA remains closed, along with the rest of nonessential federal government services in Washington, in the wake of last weekend's heavy snow, dubbed "Snowmageddon" by the administration.

Forecasting changes in weekly oil inventories can be a dicey business. Sometimes the estimates made by the industry-supported American Petroleum Institute and sell-side analysts are widely disparate; sometimes they coincide. And sometimes, like this week, they can be on either side of the numbers posted by the U.S. Energy Department.