In this chapter we look more closely at non-experimental research. We begin with a general definition of, non-experimental research, along with a discussion of when and why non-experimental research is more appropriate than experimental research. We then look separately at three important types of non-experimental research: cross-sectional research, correlational research and observational research.
- 6.0: Prelude to Nonexperimental Research
- What do the following classic studies have in common? Stanley Milgram found that about two thirds of his research participants were willing to administer dangerous shocks to another person just because they were told to by an authority figure (Milgram, 1963). Elizabeth Loftus and Jacqueline Pickrell showed that it is relatively easy to “implant” false memories in people by repeatedly asking them about childhood events that did not actually happen to them (Loftus & Pickrell, 1995).
- 6.1: Overview of Non-Experimental Research
- Most researchers in psychology consider the distinction between experimental and non-experimental research to be an extremely important one. This is because although experimental research can provide strong evidence that changes in an independent variable cause differences in a dependent variable, non-experimental research generally cannot. As we will see, however, this inability to make causal conclusions does not mean that non-experimental research is less important than experimental research.
- 6.2: Correlational Research
- Correlational research is a type of non-experimental research in which the researcher measures two variables and assesses the statistical relationship (i.e., the correlation) between them with little or no effort to control extraneous variables. There are many reasons that researchers interested in statistical relationships between variables would choose to conduct a correlational study rather than an experiment.
- 6.3: Complex Correlation
- As we have already seen, researchers conduct correlational studies rather than experiments when they are interested in noncausal relationships or when they are interested in causal relationships but the independent variable cannot be manipulated for practical or ethical reasons. In this section, we look at some approaches to complex correlational research that involve measuring several variables and assessing the relationships among them.
- 6.4: Qualitative Research
- Quantitative researchers typically start with a focused research question or hypothesis, collect a small amount of data from a large number of individuals, describe the resulting data using statistical techniques, and draw general conclusions about some large population. Although this method is by far the most common approach to conducting empirical research in psychology, there is an important alternative called qualitative research.
- 6.5: Observational Research
- Observational research is used to refer to several different types of non-experimental studies in which behavior is systematically observed and recorded. The goal of observational research is to describe a variable or set of variables. The goal is to obtain a snapshot of specific characteristics of an individual, group, or setting. Observational research is non-experimental because nothing is manipulated or controlled, and as such we cannot arrive at causal conclusions using this approach.
Thumbnail: An example of data produced by data dredging, showing a correlation between the number of letters in a spelling bee's winning word (red curve) and the number of people in the United States killed by venomous spiders (black curve). Image used with permission (CC BY 4.0 International; Tyler Vigen - Spurious Correlations).