Jennifer Zhuang

by Tuesday, February 19, 2013 @ .

I’m an economics intern at the NOAA Office for Coastal Management in Charleston, South Carolina. I work on the ENOW (Economics: National Ocean Watch) team analyzing the ocean-related economy and providing technical support. It’s a great opportunity for me to learn and practice my skills to become an applied economist. I also fell in love with Charleston because of the people, the weather, the food, the beaches…I think my work and my life now fit my Chinese first name very well, which means “peaceful ocean.” I came to the U.S. in 2010 and got my masters of natural resource economics at the University of Tennessee, Knoxville in 2012. Before that, I studied regional development at China Agricultural University in Beijing.

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Indicators for Estimating the Ocean and Great Lakes Economy

“Economic growth was good last year!”

“The new port had a huge impact on the local economy.”

“The hurricane slowed economic growth along the coast.”

While these statements provide interesting information, including specific numbers is what really gets people’s attention, which is where economic indicators come in handy. GDP (gross domestic product) is probably the first economic indicator that comes to mind. Sometimes, it goes along with another indicator, “Real GDP” (real domestic gross product), which usually appears in Time Series Datasets. For example, NOAA Office for Coastal Management’s Economics: National Ocean Watch (ENOW) uses both GDP and “Real GDP in chained (2005) dollars” to depict the Ocean and Great Lakes Economy.

So what’s the difference between GDP and Real GDP? And how should we use them?

GDP – Indicator for a Given Year

The definition of GDP is the total market value of the final goods and services produced within a country during a given year. In simple terms, “GDP is the yardstick of an economy’s performance.” People are so interested in GDP because it tends to explain a country’s economy in just one number!! This indicator also applies to subnational level (e.g., GDP by states) and industrial level (e.g., GDP by industry), and is widely used for economic descriptions and comparisons in a given year.

But GDP, which is also called “Nominal GDP,” is not a very desirable indicator to evaluate economic change over time. That’s because GDP reflects both quantity and price. We all know that prices change over time. Let’s say last year, one dollar could buy two cans of tuna, but this year, only one. In this case, GDP rise for tuna could be a result of price inflation, not necessarily expanded production.

gdp vs real gdp

Real GDP – Indicator for Growth

To prevent exaggeration in estimates of economic growth, economists usually use “Real GDP,” which takes the inflation out of GDP figures.

Until the mid-1990s, this was done by assessing the value of annual production in terms of base year prices. “Real GDP (2000 dollars),” for example, means that each year’s output is valued at the price levels that existed in the year 2000. When a set of “Real GDP” statistics are calculated by the prices from the same base year, they vary only by quantities and reveal more accurate economic growth.

Real GDP in Chained (2005) Dollars

Currently, the U.S. Department of Commerce uses the more complicated chained-dollar method to remove the effects of inflation. This method is able to address anomalies that occur when new products are introduced, when product quality changes over time, and when prices fall because of improved production techniques. The personal computer is the textbook example of this kind of change – introduced in the mid-1980s, with quality increasing and production costs declining dramatically over the next three decades. It doesn’t make sense on any level to account for the value of computers by pricing today’s computers at 1990 price levels.

Generally, “Real GDP” statistics are calculated by prices from 2005 and is labeled as “GDP in chained (2005) dollars.” Every year, Bureau of Economic Analysis (BEA) releases four quarterly GDP statistics and annual GDP in both current dollars and chained (2005) dollars.

enow national summary overview

Apply It

Now let’s take a look at the National Infographic, a summary of the 2009 U.S. Ocean and Great Lakes Economy using data from ENOW. “Nominal GDP” is used to show the number of billion dollars the U.S. ocean and Great Lakes economy produced. For the part of “2005-2009 Economic Trends,” “Real GDP in chained (2005) dollars” is used to estimate GDP growth without price inflation effect for both U.S. economy and ocean and Great Lakes economy.


Of course, no indicator is omnipotent. Indicators should be carefully selected based on the issue you are trying to explain. For example, a growing “Real GDP” does not necessarily mean an improvement of the country’s standard of living. The county’s population may increase more aggressively and people’s average standard of living is actually worse. In that case, “GDP per capita” may be one of the better indicators.

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