Confidence Intervals

In his Bad Science column in the Guardian Newspaper last Saturday Ben Goldacre wrote
"Those figures are called 95% confidence intervals, and these are one of the most useful inventions of modern life."

The column both explains what a confidence interval is and why it is so important. One must be very careful to check that increases (or decreases) over time in a statistic based on a sample are actually significant. In this case the statistic relates to unemployment and the changes observed are not big enough to conclude that the underlying population value has changed.

NOTE: The article is also available via the Bad Science web page. By the way I just love his phrase "...the gentle static fuzz of random variation"