We’ve discussed the median as a measure of central tendency of a distribution. It’s often used with income data. For example, a headline in the NYTimes a few weeks ago was “Median Income Rises, but Is Still 6% Below Level at Start of Recession in ’07.” Here is the graph which accompanied the article:
This shows a time series of national median household income since Dec 2007 (actually, it shows the percentage change in national median household income since that initial point).
This data and graph are useful for getting a picture of what happened to US household incomes over the past six years. But looking at national median household income groups together a lot of data–it’s a “coarse” statistic that ignores how household income varies geographically.
Take a look at this map of New York City that WNYC’s Data News team put together, showing “median income by census tract, as estimated by the U.S Census American Community Survey, which questioned a sample of people in each tract from 2007 to 2011.”
You can (and should!) read the accompanying WNYC article, headlined “Census Pinpoints City’s Wealthiest, Poorest Neighborhoods.”
