Comparing Quantitative and Qualitative Methods
Quantitative methods and qualitative methods, when used alone, have inherent strengths and weaknesses. Each method is good at answering some types of questions, but is less suitable to answering other types of questions. Below we compare the strengths and weaknesses of the two methods. By understanding each method’s strengths and weaknesses, you can also begin to understand how the two methods can complement one another when combined in a mixed methods study.
Quantitative methods are best suited for identifying the prevalence of a phenomenon. Because quantitative research typically asks standardized questions (i.e., everyone gets asked the same question in the same order) of a large sample of participants, this method is better suited to estimate the true prevalence of a behavior than qualitative studies which often rely on small samples of participants and the questions asked may change in both content and order depending on the issues brought up by the participants themselves.
Quantitative methods are best suited for identifying magnitude of association. Quantitative research obtains numerical data in response to questions and the statistical associations between different variables can be examined. This allows for a more objective method of assessing the strength of an association between two variables than qualitative data which relies on the textual descriptions provided by participants. Often, it can be difficult to link two concepts using qualitative data unless the participants themselves suggest the two phenomena are related. Regardless is it still difficult to assess how strongly two phenomena are related.
Quantitative methods tend to be more generalizable than qualitative methods. Due to the large samples often used in quantitative research and especially the use of probability-based sampling techniques, the findings from quantitative research are more likely to generalize to the larger population. By contrast, qualitative methods often use small samples, that are not designed to generalize, and the goal is not to generalize their findings to the larger population.
Qualitative methods are best suited for generating new insights. Because quantitative methods must have carefully scripted questions with a pre-determined set of potential responses to each question, the researcher must know before data collection begins what types of questions will be asked and what responses are anticipated. In contrast, qualitative methods allow for greater flexibility in the types and content of questions that are asked (even after data collection begins), make use of open ended questions that allow participants to suggest what issues are most relevant to the phenomenon (for them), and also allows the researcher to probe and ask follow-up questions to explore unanticipated issues that arise during data collection. Thus, qualitative methods allow the researcher to discover new and unanticipated factors brought up by the participants themselves.
Although quantitative methods allow for the examination of behavior within specific situational, environmental, or temporal contexts, the specific contexts or conditions that might influence a phenomenon must be anticipated a priori and built into the structured questions (e.g., how many cigarettes do you smoke while at work? how many cigarettes do you smoke at home?). In contrast, in qualitative methods both the researcher and the participant are freer to explore the situations or contexts in which behaviors occur (e.g., where do you smoke the most?) and they can often spontaneously emerge (e.g., well I only smoke when I am out at bars and have had a few drinks).
Unlike quantitative research in which participants must select from a predetermined set of possible responses to a question, qualitative research allows for participants to communicate their experiences from their own unique perspective and in their own words. This is beneficial to understand with greater depth and nuance the perceptions and experiences of participants and also provides the researcher with the terms and phrases that best represent the participants understanding of the phenomenon.
Quantitative research requires much more time upfront to define the exact language and response scales of the research question. Pilot testing is typically required. On the other hand, qualitative is a more exploratory and flexible method that can be changed and refined after the start of data collection.
Qualitative research typically requires more time on the back end for analysis. After data collection, the reading and analysis of text, identification of codes and themes, and interpretation and synthesis of qualitative data requires more time than typical quantitative statistical analysis.
Quantitative research tends to be a focus on much larger samples that are representative of a population. This requires a mechanism to obtain a large, representative sample of the population. In contrast, the smaller and less representative samples typically used in qualitative research may be easier and quicker to obtain.