Qualitative vs. Quantitative Research Methods in Psychology

Introduction: The Quantitative–Qualitative Debate

Social science has long debated the differences between quantitative and qualitative research. On one side, positivists argue that quantitative research is objective and measurable; on the other, post-positivists contend that qualitative analysis allows for a richer understanding of a given situation. Although qualitative and quantitative research differ in their techniques, types of data, and ethical concerns, both have an important place in psychology. The discussion below begins by exploring the realm of quantitative research before moving on to qualitative research.

Quantitative Research: Techniques and Data Types

Quantitative research uses numerical measures to evaluate the world. This approach is typically favored by positivists, who believe in objective measures as a means of predicting outcomes. The underlying epistemology holds that research can and should focus only on what can be observed and measured.

There are multiple techniques used to collect quantitative data, but all of them ultimately render data numerical. Quantitative researchers commonly collect data via surveys and questionnaires. A researcher might ask participants a series of questions to which subjects respond on a Likert-type scale, relying on self-assessment. It is also possible for a researcher to observe a situation—either natural or laboratory-based—and code responses using a Likert-type scale. The same technique can be applied in an interview setting. In each case, observations are translated into numbers that can then be assessed for statistics such as the mean, reliability, and validity.

In a study designed to analyze the investment model, the researcher used role play to manipulate a situation (Rusbult, 1980). The researcher was interested in investigating whether the investment model was applicable to romantic relationships. Because manipulating a person's actual romantic relationship would be unethical, participants were instructed to read a scenario and imagine themselves as the protagonist. Each participant then responded to items on a Likert-type scale, answering questions about what he or she would do in that situation. This illustrates one technique available to researchers who wish to use quantitative methods.

Quantitative research utilizes data placed on a scale. There are two main types: interval data and ratio data. Interval data measures values in equal increments, but there is no absolute zero. The Fahrenheit temperature scale is a classic example—the difference between each degree is measurable and equal, but no meaningful ratio can be drawn between two measurements. Ratio data, by contrast, does have an absolute zero. Age is an example of ratio data: there is an absolute zero point, namely the moment of birth. Rusbult's (1980) study uses interval data to analyze participants' responses to a hypothetical scenario.

In another example, when examining responses to dissatisfaction in romantic relationships, Rusbult, Zembrodt, and Gunn used multiple Likert-type scales, which are commonly accepted as interval data. Using interval data allowed the researchers to calculate the average response to each question. In this case, the researchers determined correlations between investment model variables and the behaviors of exit, voice, loyalty, and neglect.

Ethical Considerations in Quantitative Research

Quantitative researchers must be mindful of ethical issues. Some quantitative methods involve manipulating a situation or asking participants to recall events that may have been upsetting or even traumatic. This raises significant ethical questions. The researcher and the institutional review board must weigh whether the risk to participants is justified by the potential benefits of the study. It is essential that participation be voluntary. Accordingly, researchers must offer fair compensation that is not so substantial as to unduly influence individuals into participating. Special populations—such as prisoners or children—are granted additional protections, as these groups may be particularly susceptible to coercion.

Quantitative research often draws on large samples in order to increase statistical power and improve the ability to predict outcomes. Supporters of qualitative research, often called post-positivists, argue that by focusing exclusively on what is observable and measurable, psychologists cannot adequately explore feelings, thoughts, and perceptions.

Conclusion: Choosing the Right Method

At times, social scientists disagree about the rigorous role qualitative research plays in the field of psychology. Although some researchers rely primarily on one type of research, a better approach is to analyze the research question and hypothesis and then choose the method most likely to uncover the truth. Sometimes quantitative research is best suited to a given question; other times, qualitative research is needed. Each method has its purpose and should be selected according to the specific demands of the study at hand.

Works Cited

Bartholomew, L. M., & Horowitz, K. (1991). Attachment styles among young adults: A test of a four-category model. Journal of Personality and Social Psychology.

Monk, A. N. (1993). Mixing oil and water? Ethnography vs. experimental psychology in the study of computer-mediated communication. INTERCHI '93, 3–6.

Rusbult, C. E. (1980). Commitment and satisfaction in romantic associations: A test of the investment model. Journal of Experimental Social Psychology, 16, 172–186.

Rusbult, C. E. (1982). Exit, voice, loyalty, and neglect: Responses to dissatisfaction in romantic involvements. Journal of Personality and Social Psychology, 1230–1242.