One of the hallmarks of pseudoscience is an over-reliance on confirmation rather than refutation of a hypothesis. The antivaccine crowd are well-known for this particular violation of the scientific method. As discussed previously, science works on refutation–creating experiments that might actually disprove a hypothesis as a method to develop evidence in support of it. The anti-vaccination crowd actually hypothesizes (but not in a scientific sense) that a vaccine or set of vaccines was the causal factor in some side effect (autism, death, or whatever else), then they should establish an experiment (double-blinded of course) that would refute that hypothesis. If at some point, the data cannot refute it, then the anti-vaccinationists would have supporting data for their particular supposition.
But instead of actually performing experiments (which cost money, which may show that they are wrong, or which might not be ethical), they resort to mining data to prove their point. Data mining is dangerous, because confirmation bias, that is, finding information or data that supports a belief while ignoring all other data that does not, makes the data suspect or even useless.
So, in that vein, the anti-vaccinationists often mine data from any database they can find, such as the Vaccine Adverse Event Reporting System (VAERS), which is a program for vaccine safety, managed by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). VAERS functions as a post-marketing safety surveillance program (similar to other programs for almost every regulated medical device and pharmaceutical) which collects information about adverse events (whether related or unrelated to the vaccine) that occur after administration of vaccines.
VAERS has numerous limitations, including lack of scientifically designed questions, unverified reports, underreporting, inconsistent data quality, and absence of an unvaccinated control group. VAERS is basically a collector of information, but has limited value in making conclusions since it does not provide information that is obtained in a controlled manner. However, it does have some usefulness, in that certain trends may be spotted given enough time and data points.Read More »Anti-vaccine lunacy–more lies about Gardasil