### A study that is statistically significant

"A study that is statistically significant has results that are unlikely

to be the result of random error . . . ." Federal Judicial Center, Refer

ence Manual on Scientific Evidence 354 (2d ed. 2000). To test for

significance, a researcher develops a "null hypothesis"--e.g., the asser

tion that there is no relationship between Zicam use and anosmia. See

id., at 122. The researcher then calculates the probability of obtaining

the observed data (or more extreme data) if the null hypothesis is true

(called the p-value). Ibid. Small p-values are evidence that the null

hypothesis is incorrect. See ibid. Finally, the researcher compares the

p-value to a preselected value called the significance level. Id., at 123.

If the p-value is below the preselected value, the difference is deemed

"significant." Id., at 124.

..

For the reasons just stated, the mere existence of

reports of adverse events--which says nothing in and of

itself about whether the drug is causing the adverse

events--will not satisfy this standard. Something more is

needed, but that something more is not limited to statisti

cal significance and can come from "the source, content,

and context of the reports," supra, at 15. This contextual

inquiry may reveal in some cases that reasonable inves

tors would have viewed reports of adverse events as mate

rial even though the reports did not provide statistically

significant evidence of a causal link.

MATRIXX INITIATIVES, INC., ET AL. v. SIRACUSANO

ET AL.

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR

THE NINTH CIRCUIT

No. 09-1156. Argued January 10, 2011--Decided March 22, 2011