¶ … measure situations of reality (Piquero, 2002). A dependent variable and an independent variable are studied for patterns of relation, covariance, and cause and effect. For example, the relationship between impulsivity, the independent variable, and criminal behavior, the dependent variable, or the effects of a mandatory arrest policy, the independent variable, on future patterns of domestic violence, the dependent variable, are both examples of quantitative research. For causality, three criteria are needed. In association, the variables must be related to each other. The independent variable must precede the dependent variable in time order. And the issue of no spuriousness, which occurs if there is no third variable observed. Surveys are mostly used for observation within the social sciences, such as behaviors or the general public has feeling about certain issues. Experimental and quasi-experimental research is best to study the cause and effect situations. True experiments must have three features: two comparison groups, one experimental and one comparison, variation in the independent variable before assessing for change in the dependent variable, and random assessment of the two comparison groups. An important consideration for the approach is to identify the effects of randomization in order to generalize the findings regarding the cause and effect relationships. Quasi-experimental research does not have random assigning to the experimental and control groups.

Two types of quasi-experimental designs exist. The nonequivalent control group is experimental and control groups are designated before treatment. The before and after designs both have pretests and posttests, but no comparison group. An example of a nonequivalent control group would be a study of the effects of police actions on the seat belt law violations. Before and after design examples could include the impact of the gun law.

An example would be male respondent's involvement in delinquent acts and emotional ties to social bonds. Panel and cohort, longitudinal research, is studies of the same group over a period of time and are concerned with assessing within and between the group exchanges. Panel studies follow the same group. The cohort studies examine specific populations.
Time series design involves variations of multiple observations for the same group over time or certain points in time. They are used to analyze a single variable at successive times and are useful for studies of impacts of new law or social programs. They are also useful for studies of trends that are influenced by intervention techniques. But, they have the inability to control potential spurious events. The third variable can affect the results.

Meta-analysis is a quantitative research analysis of findings from multiple studies, such as broken homes and delinquency. Researchers have learned that it is not appropriate to base conclusions on one study. Analysis of data from multiple studies gives more validity to the data being analyzed and gives a truer picture of the findings.

It is common in criminology to use qualitative data to create quantitative data sets (Miller). Data from observation studies for police decision making, or impacts of police actions on citizen behaviors, as well as official narrative reports, such as police incident reports for homicide and other crimes, are used to create sets of quantitative data. These quantitative sets are used in conjunction with other quantitative data sets for statistical comparison studies to determine findings in reality situations, such as housing sales in high crime neighborhoods and how they are related.

Quantitative studies are used to study distribution and causes of crime (Quantitative methods in…