In addition to point estimates (e.g., % approving of President Barack Obama’s job performance), public opinion polls are often used to determine what factors explain a given attitude or behavior. For example, is education level or gender more predictive of Obama approval? This type of analysis involves testing the effects of multiple variables simultaneously. One possibility that researchers have discussed is that while some nonprobability samples may not provide very accurate point estimates, they might be able to provide accurate information about how different factors relate to one another (i.e., multivariate relationships).
To test this, we identified four outcomes (smoke daily, …read more
Source: Pew Research