What is the test for negating a finding that a jury found a defendant guilty on a different basis than on the basis of reasonable doubt?

The court quoted with approval from United States v. Townsend (7th Cir.1991) 924 F.2d 1385, 1414: " 'It is one thing to negate a verdict that, while [4 Cal.4th 1126] supported by evidence, may have been based on an erroneous view of the law; it is another to do so merely on the chance--remote, it seems to us--that the jury convicted on a ground that was not supported by adequate evidence when there existed alternative grounds for which the evidence was sufficient.' " (Griffin, supra, 502 U.S. at p. ----, 112 S.Ct. at p. 474.)