I'm trying to do some research on unemployment and labor participation rate in the US to figure out what people are talking about.
For instance, the Civilian Labor Force Participation Rate for Sept 2016 is 62.9% (FRED 1). My attempt to control for retirement would be to look at the 25-54 age group series, which puts the labor participation rate at 81.7% (18.3% unparticipation) (FRED 2), but I'm guessing there a number of things wrong with that approach. The Bureau of Labor Statistics says the U-6 unemployment is
Total unemployed, plus all persons marginally attached to the labor force, plus total employed part time for economic reasons, as a percent of the civilian labor force plus all persons marginally attached to the labor force
and gives the Oct 2016 number as 9.5% (BLS 1). This sounds like an all-inclusive definition, or what people "really" mean when they talk about unemployment, but that differs from the 25-54 labor participation rate by quite a bit (9.5% vs 18.3%).
Question
In what way is the labor participation rate useful for tracking unemployment? It seems there are a large number of people included in labor participation that shouldn't be included when trying to measure unemployment, for example, the number of people retired and choosing not to work.
(side question: is there a number of people retired series on FRED? I'm not seeing one...)