Various methods for conducting research exist within the criminal justice field. Hypotheses formulated when conducting research are often influenced by the type of research that is conducted. Criminal justice or criminology research is often conducted with the intention of providing scientific information to major decision-makers within the field who may then implement plans to handle crime based on these studies.

Quantitative and Qualitative Research

Quantitative research design in criminal justice involves the use of statistical data in an attempt to predict a given outcome. Quantitative research can involve many variables which are studied in an attempt to find patterns or correlations between the statistical data and what the researchers assume to be the potential outcome. On the other hand, qualitative research in criminology involves looking at the bigger picture. Qualitative research is not concerned with what statistical data can tell us about crime, but rather what the statistical data may tell us about the larger context. Qualitative research methods provide a more dynamic understanding of crime and criminal behavior. Qualitative research is considered by many to be inferior to quantitative research because it overemphasizes interpretation rather than simply looking at what the statistical data indicates.

Survey Research

Similar to quantitative research, the use of survey-based research in criminal justice revolves around the use of statistical data. Hypotheses developed through this type of research generally concern how a given population or the general population is likely to respond to various issues in criminology. The Sam Houston State survey research program indicates that the primary purpose of survey research is to inform the general public and public officials with an accurate picture of attitudes towards different types of crime and various ethical and legal issues in the criminal justice system. This type of research can be important, because it can provide legislators with an understanding of how to act regarding various important issues that affect the ability of law enforcement officials to conduct business.

Time-Series Research

Time-series design in criminal justice research involves the study of one group over a long period of time. The types of groups studied in this type of research can be one type of individual (e.g., sex offenders) or a group of people (e.g., a town). The purpose of the time-series research method is to try to better understand how people act throughout the duration of their life and whether or not that behavior is indicative of a certain pattern of behavior. These trends that sometimes emerge sometimes indicate whether or not a certain type of intervention by law enforcement officials or legislators has been effective. Researchers should be aware, however, that research over long periods of time may give rise to unaccounted for variables which could skew the conclusions reached as a result of the study. For instance, it is easy to conclude that a law allowing people to carry concealed weapons led to a decrease in crime in a given town over a long period of time. However, if it turns out in fact that much of the crime prior to the law was committed by a family who later moved out of state to conduct their crime spree elsewhere, the conclusion would be flawed because it does not account for this fact.