Coruscation

"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.

-- supremecourt.gov/opinions 09-1156