Commerce Seeks Comments on Statistical Test After Federal Circuit Ruling in Dumping Cases
- Schulz Trade Law
- May 21
- 3 min read
Updated: May 26
Commerce Seeks Comments on Statistical Test After Federal Circuit Ruling in Dumping Cases
May 20, 2025
On May 19, 2025, The U.S. Department of Commerce (Commerce) published a notice on dumping cases asking for comments and alternatives on Commerce’s current use to the Cohen’s d test. Comments are due by May 30, 2025.
The request for comments on this long controversial differential pricing analysis comes after the Court of Appeals for the Federal Circuit in Marmen v. United States (April 22, 2025) recently held that Commerce’s use of the current Cohen's d test is unreasonable when the test is applied to data that does not satisfy the statistical assumptions of normal distribution, equal variances, and sufficiently numerous data.
Federal Circuit’s Ruling in Marmen v. United States
In antidumping investigations, Commerce uses a method called “differential pricing analysis” to determine how to calculate a company’s dumping margin. One part of Commerce’s pricing analysis requires a Cohen’s d test, a statistical tool used to assess whether significant differences exist in the prices a company charges to different customers, regions, or during different time periods. The Cohen’s d test is not required under any statute or regulation, but instead is a method Commerce created as part of its internal approach to analyzing pricing differences. Federal Courts have upheld Commerce’s Cohen d practice largely until now.
Role of Cohen’s d Test in Antidumping Investigations
The Cohen’s d test helps Commerce to evaluate whether a company charged noticeably different prices to certain customers or in certain situations. If Commerce does find that a company charged noticeably different prices to certain customers, it can decide that the company’s pricing pattern justifies using a different calculation method (average-to-transaction method), which typically results in higher margins. This method also allows Commerce to apply “zeroing”, which increases a company’s exposure because Commerce will ignore sales where dumping did not occur in its dumping margin calculation.
Implications of Differential Pricing Analysis
Foreign producers often challenge the assumptions and groupings under Cohen’s d, especially around normal distribution assumptions and pooled standard deviations. U.S. domestic industry may advocate for the use of Cohen’s d if they believe that respondents are engaging in targeted dumping across purchasers, regions, or time.
Key points
Commerce’s Request for Comments
On May 19, 2025, the U.S. Department of Commerce published a notice requesting comments and alternatives to its use of the Cohen’s d test in differential pricing analysis, with a deadline of May 30, 2025.
Federal Circuit Ruling
Cohen’s d Test Role
Impact on Dumping Margins
Stakeholder Perspectives
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