Charles Murray, in a somewhat dated paper, writes:

Here I summarize one of the main results of that inquiry, half hopeful and half disturbing. The hopeful half is that poverty in America is seldom the result of uncontrollable events involving the economic system. I will argue that the old wisdom—that anyone who is willing to work hard can make a decent living—has much more truth to it than has recently been acknowledged. The disturbing half is that our current popular understanding of the poverty population may be very wide of the reality. I conclude with a proposal for clarifying the situation.

The more general statement is that poverty among the working-aged in 1970 was a phenomenon among people with less than a high school education, who constituted a remarkable 75 percent of working- aged adults below the poverty line.[3] That most poor people are ill-educated does not mean that most ill-educated people are poor. On the contrary, 90 percent of them were not poor in 1970, 90 percent were not poor in 1980, and 84 percent were not poor in either year. But three out of four people who were poor came from that group.

Poverty is the elephant of social policy, with social scientists playing the role of the groping blind men. We each describe a different appendage without really contradicting one another. In this case, I have asked a specific question regarding people who are in the labor market and reached the conclusion … that it is extremely rare for a person to get into the labor market, stick with it, and remain poor…. Suppose, however, I had made just one different assumption, that people who are not in the labor market are discouraged workers, out of the labor market only because they know there are no jobs (or only “dead-end” jobs). Presto: The portrait can be made to flip completely, and the nation becomes once more a country with structural poverty woven inextricably throughout the economy.

The full paper can be found here. Link and quote via Division Of Labor here.