Story time

A new study released by the American Public Transportation Association (APTA) shows that people who live in communities with extensive public transportation networks exercise more, live longer, and are generally healthier than people in automobile-dependent communities. (Via Inhabitat blog)

So far so good. They found that the presence of public transport is correlated with public health.

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Then the teacher declares story time, and then up is down, and left is right.

The headline writer tells us: REPORT SAYS PUBLIC TRANSPORTATION MAKES YOU SKINNY. It said nothing of this sort.

APTA president makes up this chain of cause-effect, with no supporting evidence:

Use of public transit simply means that you walk more which increases fitness levels and leads to healthier citizens. More importantly, increasing use of public transit may be the most effective traffic safety counter measure a community can employ.

Here are some other stories for your reading pleasure:

1. Public transport typically are better developed in cities. Younger people happen to prefer living in cities. Younger people exercise more and are typically healthier.

2. Cities that have extensive public transport typically also have an abundance of restaurants and food stores. Having lots of food around tempts people, and they tend to eat more than they need. They get fat and unhealthy.

3. Places with great public transport are mostly cities. Cities are crowded, polluted and have a dearth of outdoor space. City dwellers do not exercise as much, and they get unhealthy.

4. Places with great public transport are mostly cities. Cities are crowded, polluted and have a dearth of outdoor space. Because of scarcity, city dwellers value green space more, and therefore they tend to spend more time there and get healthier.

5. Large cities have plenty of distractions from healthy activities. Night clubs, movie theaters, Broadway shows, karaoke, shopping malls, etc. all take up valuable time that should otherwise be used for exercising. Therefore, people are less well in cities.

6. City dwellers are vain people who must look good. Looking good means being skinny, according to the fashion mavens. Thus, people exercise more and eat healthy.

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Ok, you get the picture. There are no end to telling stories. The one thread linking all these stories is that there is not a shred of evidence to support any of the logic. The data that is cited merely states the correlation between A and Z, and tells us nothing about A causing B causing C causing... Z.

Taleb calls this the "narrative fallacy". Our minds are very active and very successful in making up stories. Unfortunately, most of them are junk, and nothing more.

Comments

[Tom Hopper]

Excellent point about the "narrative fallacy." I see this all the time in print news, and am often left wondering if there was information edited out of the article.

Having lived in both automobile-dependent areas (especially metro-Detroit) and areas with good public transportation (parts of Europe), I would suspect that good public transportation and getting around by foot are positively correlated by sharing common causal factors, such as density of shops and other "destinations." This is similar to your previous speculation about the relationship between Alzheimer's and certain proteins obtained by spinal tap.