Meta-analysis can be viewed as a kind of research endeavor in itself and an alternative to other, primary research strategies. Meta-analysis can be used for a wide range of research questions or hypotheses. There is a sense in which a meta-analysis is like a survey. In meta-analysis, the investigator must often deal with a disconcertingly wide variety of operationalizations chosen by other researchers. Faced with inconsistent results in the research literature, researchers in earlier times were forced to rely on subjective judgments, perhaps supplemented by crude methods of description and summary. Researchers have begun to use sophisticated statistical methods that allow them to combine the results of several independent studies and arrive at conclusions with a precisely stated degree of confidence. The term meta-analysis is used to refer to these methods. With primary research methods methods, the researcher formulates a hypothesis, designs a study to test it, gathers the data, and interprets the results.