Here are the monthly average retail gasoline prices in the USA since 1976:

Take a few seconds to examine the overall price trend and the points where there are major changes in the price of gasoline.

Now that the price changes are fresh in your memory, consider some basic facts:

• Oil is a finite resource.
• Oil is a fungible commodity.
• Population is increasing.
• Car ownership in China and India has increased dramatically in recent years.

Now, consider the dates of several historic events, including:

• Important revolutions
• Market bubbles popping
• Major terrorist attacks
• Major recessions

This is enough to have a reasonable understanding of the price of oil, without a more detailed look. With this understanding of the context of gas prices, consider:

• Given the information above, how much control does the President of the United States have over the price of gasoline?
• If you had to choose one price or trend to represent the cost of gasoline under President Bush or Obama, what would be the most honest price or trend in prices?
• What points do the Republican presidential candidates reference as the price of gas under Presidents Bush and Obama?
• What (if any) price trend do the Republican presidential candidates mention as the trend under Presidents Bush and Obama?

It should now be clear that the major GOP presidential candidates are either misinformed about the price of oil, or are intentionally deceptive. Which is more probable? Is one of these alternatives acceptable?

[Update 2011-11-28] These statistics are a bit old, but I haven’t been able to locate good numbers that are more up to date. I’d greatly appreciate any pointers to more recent numbers.

(This is a re-post from last week. The original post disappeared in the server change.)

I saw a graph of car and bicycle production in The Economist. The article was On your bike: Obesity and high oil prices are good news for the world’s biggest bikemaker. This was one of the many recent stories on the increase in gas prices leading to more people riding bikes. The graph looks something like this:

Bicycle and car production (1950—2007)

Car production is increasing as expected, but bike production is even higher. But does this plot tell us anything useful? Doesn’t world population growth look similar? I found that world population looks like this:

World population (1950—2007)

This is a huge increase. To make the bicycle production plot more useful, I can find the per capita production. Just divide the production by population:

Per capita car and bicycle production (1950—2007)

This is a much more useful plot. Bicycle production is going up, but not as fast in the original graph. The current production is actually slightly lower per capita than in the late ’80s. The flatness of the car production line is surprising. I also added a five year moving average to the plot.

Since there are so many articles linking bicycling to gas prices, lets look at the price of gasoline. Because of inflation and other factors, the absolute price of gas isn’t very useful. I found the consumer price index adjusted gas price:

US CPI adjusted gasoline prices (1950—2007)

Hmm… that doesn’t look as bad as you would expect. This graph does make it really obvious that the data I am using stops in 2007. I can now add the gas price to the production plot. The production scale is on the left, the price scale is on the right:

CPI adjusted gas prices and global car and bicycle production (1950—2007)

Interesting. The gas price and bike production don’t match at all before the mid ’90s. The match for the past ten or so years is pretty good.

These are just some thoughts on getting useful information from graphs. I didn’t do any actual statistics, but this gives some ideas for how to make these plots more useful.

I highly recommend reading How to Lie with Statistics by Darrel Huff.

Sources:

• The Economist: On your bike: Obesity and high oil prices are good news for the world’s biggest bikemaker
• Earth Policy Institute: Economic Indicators: Bicycles
• U.S. Census Bureau: International Database
• U.S. DOE Energy Information Administration: Peal Petroleum Prices