Know about data collecting

We can often be fooled into what is factual information from the providing source. For instance, most of us have heard about the unemployment rate in the U.S. In December 2008, it was around 7.2%. But where does this information come from? The Bureau of Labor statistics at http://www.bls.gov/ collects the information and that's a credible agency. However, how they collect the data leaves much to be desired. Here's what they note on their website (with a bit of digging):

"Because unemployment insurance records relate only to persons who have applied for such benefits, and since it is impractical to actually count every unemployed person each month, the Government conducts a monthly sample survey called the Current Population Survey (CPS) to measure the extent of unemployment in the country. The CPS has been conducted in the United States every month since 1940 when it began as a Work Projects Administration project. It has been expanded and modified several times since then. As explained later, the CPS estimates, beginning in 1994, reflect the results of a major redesign of the survey.

"There are about 60,000 households in the sample for this survey. The sample is selected so as to be representative of the entire population of the United States. In order to select the sample, first, the 3,141 counties and county-equivalent cities in the country are grouped into 1,973 geographic areas. The Bureau of the Census then designs and selects a sample consisting of 754 of these geographic areas to represent each State and the District of Columbia. The sample is a State-based design and reflects urban and rural areas, different types of industrial and farming areas, and the major geographic divisions of each State" (Bureau of Labor Statistics, 2001, para. 6-7).

While they are using a large enough sample base for statistical data, the data is actually a scientifically-based guess. There are other ways to collect the data, such as gathering unemployment checks sent out by the different states, but even that information leaves out those who have gone off unemployment via maxing out their benefit. This too would be a scientifically-based guess.

When researching and writing your papers, it helps to understand where the data came from and how it was collected. It also helps to determine if the information can be verified by others.

Reference:
Bureau of Labor Statistics. (2001). How the government measures unemployment. Retrieved February 2, 2009, from http://www.bls.gov/cps/cps_htgm.htm