Both qualitative and quantitative research methods have the potential to yield reliable, valid, and important information that can be used to inform public policy. Criminal justice researchers use a wide range of research methods, which vary depending on the research questions, the purpose of the study (applied versus pure research) and the overall paradigm and theoretical framework. Research can be used to validate or disprove an existing theory, alter or enhance an existing theory, generate a new theory based on phenomenology, or evaluate the effectiveness of a policy, program, or intervention (“Criminology Research Methods,” n.d.). Qualitative research methods are best used when the researchers are interested in participants’ perceptions, or seek open-ended answers to questions. Quantitative research methods are best used when the researchers want hard data in numerical form, which can be used to generate statistical analyses. Mixed-methods approaches can be tremendously helpful for criminal justice and social science researchers because of the fluid nature of social reality. Within the two broad categories of qualitative and quantitative methods, researchers have options for how to design their study and test their hypotheses. Qualitative and quantitative designs share some elements in common. Both qualitative and quantitative research begin with exploring topics of interest, perhaps within established theoretical boundaries. Furthermore, both qualitative and quantitative research starts by either taking...

Both quantitative and qualitative research methods rely on sampling a population. Ideally, random sampling is used to enhance internal and external validity. Other methods of sampling, such as convenience sampling, can harm validity whether the research is qualitative or quantitative. The main difference between quantitative and qualitative design is that the former yields numerical and/or statistical data, but there are other differences between these two methods that should be apparent to criminal justice researchers. For instance, whereas almost all qualitative research will be values-driven, quantitative research can generate raw data, simply numbers that are not guided by any research questions or the need to apply the results of the study to public policy or criminal justice programming. While there are certainly qualitative research designs that are exploratory and therefore not necessarily linked to a particular research hypothesis, most qualitative studies will be conducted for some practical human interest or relevance for applied criminology (Higgins, 2009).
There are two broad types of criminal justice research, each of which can be sub-divided into different designs. Quantitative research designs include experimental, quasi-experimental, and non-experimental. Cross-sectional designs, cohort designs, causal designs, and longitudinal designs are also…