But observational studies do not demonstrate causality.
The studies are correlational, so do not demonstrate causality.
Analyses can establish statistical relationships, but it has been difficult to demonstrate causality with any certainty.
The data do not demonstrate causality but may reflect self-medication or a shared risk factor.
This link should underpin future studies designed to definitively demonstrate causality.
Since such correlational research cannot demonstrate causality, a number of researchers have called for the increased use of experimental methods for theory testing.
Authors from the department for primary care and public health services at King's, writing in the British Journal of General Practice, recognise that their study could not demonstrate causality, nor could such aggregated data determine whether patients in the survey had actually been prescribed an antibiotic or refused one in the previous year.
After reviewing the data, the committee concluded that the evidence for the benefits of high levels of vitamin D was "inconsistent and/or conflicting and did not demonstrate causality".
That's because to demonstrate causality, engagement and performance data would have to be gathered at different points in time, to test whether increases in engagement levels translate into subsequent increases in performance, and whether decreases in engagement levels translate into subsequent decreases in performance.
The IOM committee's report, released this morning, says evidence for many of the health claims for vitamin D is "inconsistent and/or conflicting or did not demonstrate causality". The exception is the vitamin's well-documented (and noncontroversial) benefits on bone growth and maintenance.
Finally, we are able to demonstrate association, but not demonstrate causality.
