Dyson, Inc. recently challenged claims made by competitor Sharkninja Operating LLC that “2 out of 3 preferred the Shark” and “America preferred... Shark,” which Shark claimed were supported by an independent in-home study.

Although the 355 participant, double-blind study provided by Shark was performed by independent third-party experts, the National Advertising Division (NAD) found certain aspects of the study’s methodology flawed: 1) the study gave participants only two weeks per vacuum tested (a total of four weeks); 2) there was no standardization of how often and under what conditions the participants had to use the vacuums; 3) there were no follow up question to determine the extent of actual usage. Notably, most participants indicated in a pre-study survey that they vacuumed two-to-three times per month, so a test period of two weeks may have only yielded one-to-two uses of the tested-vacuum. The NAD also noted that Shark used a testing period of four-five weeks in its own internal testing indicating a longer test period was both feasible and potentially more accurate and reliable.

As such, NAD determined the conclusions from the study could not form a reasonable basis for the challenged preference claims.

TIP: In order to support preference claims, advertisers should confirm that testing conditions are tailored to the specific product, including environment, time, and use conditions.