What is the difference between:
the first bullet on page 13 here: "In 2011, the official poverty rate was 15.0 percent. There were 46.2 million people in poverty"
the first bullet on page 1 here: "In 2011, about 15.9 percent of the U.S. population had income below the poverty level, an increase from 15.3 percent in 2010. The number of people in poverty increased from 46.2 million to 48.5 mil-lion during the same time period."
The first is from the Current Population Survey and the second from the American Community Survey, as explained in How We Measure Poverty and Income.
"Many people contact us each year asking how to know which estimate to use for a particular purpose. For national estimates, we recommend the CPS because it provides a consistent historical time series at the national level and can also be used to look at limited state-level trends. However, because of the larger sample size and smaller sampling errors we recommend using the ACS for subnational geographies."