Becker has for seventy years been mulling over the problem of evidence. He argues that social scientists don’t take questions about the usefulness of their data as evidence for their ideas seriously enough. For example, researchers have long used the occupation of a person’s father as evidence of the family’s social class, but studies have shown this to be a flawed measure—for one thing, a lot of people answer that question too vaguely to make the reasoning plausible. The book is filled with examples like this, and Becker uses them to expose a series of errors, suggesting ways to avoid them, or even to turn them into research topics in their own right. He argues strongly that because no data-gathering method produces totally reliable information, a big part of the research job consists of getting rid of error. Readers will find Becker’s newest guidebook a valuable tool, useful for social scientists of every variety.