While the general public may find anecdotal evidence highly compelling, most scientists are suspicious of data the rests on anecdotes. The idea that research can be based solely on pooling more than one anecdote to create data is problematic - more than one anecdote is simply just – more anecdote(s) not data.
There are many reasons why studies that rely on anecdotal information cannot be validated. For one, the study results/symptoms are vague and can’t be well defined. The problem being that rhetorical symptoms are subjective and rely on an individual’s recollection and judgment. For example a symptom defined as a sinus/respiratory issue could include a simple lingering regular cold. Anecdote-based studies offer vague outcomes that are interpreted subjectively. Subjective findings should not be allowed to take the place of quantitative measures and physical findings. The study done by the Texas Department health which set out to determine the relationship between natural gas activities and health relied on physical findings. The study used physical (blood levels) evidence to determine if there was a relationship between air emissions and the resident’s health. In its conclusion, the researchers found no connection (Dish - Texas Department of Health Consult). This report casts doubt on the connection of air emissions to health issues; unlike the anecdotal reports from residents experiencing self-reported symptoms. This does not imply that residents did not experience symptoms they described but that the symptoms could have been caused by another source.
Another problem with studies based on anecdotal responses is confirmation bias, where researchers tend to seek out information that confirms what they already believe, want to believe or want to avoid. The study released today by Earthworks, Oil and Gas Accountability Project, Gas Patch Roulette, an anecdotal based study, references another study that was also based on anecdotal findings (Bamberger, M. and Oswald, Robert E. “Impacts of Gas Drilling on Human and Animal Health.” New Solutions: A Journal of Environmental and Occupational Health Policy. Vol. 22(1)51-77, 2012.).
The placebo effect also comes into play. The media constantly covers the potential health risks associated with natural gas development and in process broadcasts the shared symptoms. This may have altered or influenced the way an individual recollected or reported an ailment.
On the bright side, these recently released reports, the Grassroots Environmental Education's “Human Health Risks and Exposure Pathways of Proposed Horizontal Hydrofracking in New York State” and the Earthworks report offer an opportunity to bridge the “facts” and “belief” gap. These two documents offer the crux of anti’s argument against natural development. It is an opportunity to offer the reasons, point by point, why safe natural gas development can occur without the assumed human health impact.
Changing people’s perception about anecdotes is asking people to mistrust their feelings. It is not an easy task. People tend to strongly believe that personal experiences override objective quantitative evidence, even when good objective studies offer different conclusions. They tend to conclude that the objective study is wrong and work hard to find fault in it. They even go further; they believe the personal stories without any proof and without even trying to verify the story themselves; to them personal stories stand firmer than physical evidence supported studies. Health is not a matter personal opinion but a matter of objective facts. Senator Daniel Patrick Moynihan said it best – “You are entitled to your opinion. But you are not entitled to your own facts.”