Correlation implies causation – when it does or does not with vaccines

correlation implies causation

I originally wrote this article in 2014 to discuss whether correlation implies causation. Not that I expect everyone to read and remember this one article, but it’s frustrating when I see a conversation where people who deny science and accept science both misuse correlation and how it relates to causation. So, I decided to update this article and republish it as a reminder that the relationship of correlation to causation isn’t as easy as a simple trope or meme.

One of the foundations of biomedical science is whether correlation implies causation. Anti-vaccine activists often conflate or misunderstand the two, rejecting or accepting correlation as it fits its narrative.  The “correlation implies causation” story is often abused, misused and confused by many writers.

One thing we do know about correlation is that if you can’t establish correlation, despite numerous attempts, it is nearly impossible to claim causation. Also, if you do observe correlation, it also doesn’t imply causation. 

But there are methods, grounded in powerful science, to establish causation from observations of correlation. So sometimes correlation does not imply causation. But sometimes correlation implies causation. 

This article will help show how we may be able to establish causation from observations of correlation. And, like all science, this is hard stuff. Continue reading “Correlation implies causation – when it does or does not with vaccines”

Electronic cigarettes – what is science saying as of today?

electronic cigarettes

Over the past few years, electronic cigarettes (often called a personal vaporizer, e-cigarette, or many other trendy descriptions–I’ll abbreviate them as EC, just to save space) have become a popular alternative to tobacco cigarettes. They originally were developed as a tool to quit cigarette smoking, which is factually linked to lung cancer and other respiratory diseases.

However, ECs have become much more than a tool to end smoking, but they have evolved into popular subculture phenomenon known as the “vaping community” that, in many respects, seem to mimic the marijuana advocates. The vaping community continues to push a belief that ECs are safer than traditional cigarettes, have little health risk to the vaper (electronic cigarette smoker), and is much more socially acceptable than smoking cigarettes or cigars.

One of the most ironic and amusing stories about ECs is that Jenny McCarthy, the antivaccination expert who thinks that all ingredients in vaccines are dangerous, has become an advocate for vaping. I bought a brand new, upgraded version 4.7, nuclear powered irony meter, and it just broke. It’s possible Jenny caused a nuclear accident in my house.

What are the dangers of electronic cigarettes? Are there any at all?

Continue reading “Electronic cigarettes – what is science saying as of today?”

Electronic cigarette dangers – new research

electronic cigarette dangers

Note – this article has been updated with new research and information about electronic cigarette dangers. Please comment there, as the comment section for this article is closed.

Over the past few years, electronic cigarettes (often called a personal vaporizer, e-cigarette, or many other trendy descriptions–I’ll abbreviate them as EC, just to save space) have become a popular alternative to tobacco cigarettes. They originally were developed as a tool to quit cigarette smoking, which is factually linked to lung cancer and other respiratory diseases.

However, ECs have become much more than a tool to end smoking, but they have evolved into popular subculture phenomenon known as the “vaping community” that, in many respects, seem to mimic the marijuana advocates. The vaping community continues to push a belief that ECs are safer than traditional cigarettes, have little health risk to the vaper (electronic cigarette smoker), and is much more socially acceptable than smoking cigarettes or cigars.

Continue reading “Electronic cigarette dangers – new research”

Correlation does not imply causation – except when it does.

correlation

Editor’s note – this article has been substantially updated, and the new version has been republished here.

One of the central tenets of the pro-vaccine world is that correlation does not imply causation – but it is misused and frequently abused by many writers. We, the pro-science/pro-vaccine world, dismiss correlation, if real correlation can be shown, as robust evidence indicative of any causal relationship.

Conflating causation and correlation is somewhat different than the logical fallacy of post hoc ergo propter hoc, where one thinks one event follows the first event because of the existence of the first event. I’m sure all good luck charms and superstitions, like walking under a ladder, are related to the post hoc ergo propter hoc fallacy. So if I walk under a ladder, then trip on a black cat, then crash into a mirror, I don’t immediately blame the initial act of walking under the ladder. I just assume I’m clumsy.

Correlation and causation are a very critical part of scientific research. Basically, correlation is the statistical relationship between two random sets of data. The closer the relationship, the higher the correlation. However, without further data, correlation may not imply causation, that the one set of data has some influence over the other. Continue reading “Correlation does not imply causation – except when it does.”

Smoking cannabis doesn’t cure cancer but it may cause it

Marijuana_Cures_CancerAs I have written before, there is a lot of controversy about medical uses for marijuana, although it appears to be much more of a political debate than a scientific one. There just isn’t much evidence that supports a hypothesis that marijuana has any significant therapeutic effect on diseases like cancer, neurological disorders, or other diseases.

Scientists have long suspected that smoking marijuana could be linked to lung cancer, but there has only been weak evidence supporting a causality.  Recently, a 40 year review of  over 49,000 men strongly suggests that smoking cannabis does indeed increase the risk of lung cancer. The study examined 49,321 men between the ages of 18 and 20 who were being enlisted in the Swedish military between 1969 and 1970, examining their health and lifestyle issues, along with their use of marijuana. The researchers reviewed other potential risk factors such as respiratory disease, other types of smoking, and socioeconomic status. Continue reading “Smoking cannabis doesn’t cure cancer but it may cause it”