Shatter? Not Likely

This is a recent headline from HybridCars.com - Study Shatters Myth of Hybrid Premium. The story goes on to talk about a study by Topline Strategy Group in which they looked at why people buy hybrids, what their demographics are and how satisfied they are with their purchase.

Too bad the study really doesn't shatter anything. With 118 Prius drivers who were located by putting fliers on their windshield, this study proves nothing about hybrid drivers in general. In fact, I would go so far as to say it proves nothing beyond what these 118 people had to say.

The issues I have are many. First, only 118 people gives you a very small sample size. Which means your confidence intervals are of necessity very wide. Two, this is nowhere near a random sample of hybrid drivers. People who buy a Prius could be extremely different from those who buy an Escape Hybrid (SUV buyer vs sedan consumer, think about it).

As for whether this study 'shatters myth of hybrid premium,' its extremely unlikely. Despite the following two items from the study:

• When asked what kind of car they would have purchased if they had not bought a hybrid, these shoppers would have purchased a vehicle costing thousands of dollars more than a Prius.
• Most of the respondents used longer periods of ownership and higher gas prices than usually used by journalists.

Subjects are notoriously bad at coming up with facts and numbers in questionnaires. So, just because these people are reporting they are paying more for gas doesn't mean all that much.

Also, only those who feel strongly about a subject matter are likely to respond. Those who are feeling ok about their car aren't likely to respond to a flyer like this. So when you see the following numbers:

• 71 percent of respondents earned more than $100,000 per year.
• 73 percent were 40 years or older.
• 58 percent were men.
• 88 percent were “very happy” with their Prius; 12 percent were “somewhat happy.”
• Most bought their prius because they wanted an eco-car.

You should be asking questions like: Where was this study done? Was it in California, where many drivers may have been motivated by access to the HOV lane? Were the fliers distributed in a city or a suburb? A parking garage for commuters? All of these things would affect who was responding.

When I first saw the press release on this study, I thought it was worthy of being ignored. Now that I have looked a little more closely at it, I'm glad I did.