Quantitative research plans mainly use deductive reasoning and generalizations in research. Quantitative research is most often associated with quantifying the relationship between the independent or predictive variable and the dependent or final variable. In general, quantitative research plans are classified as non-experimental or experimental. The two common types of quantitative descriptive models in nursing are case-control and comparative analysis. Case-control studies include cases with or without pre-existing disease or exposure.
Comparative studies examine differences in several variables, which can occur in two or more units. Correlation designs involve a systematic study of the nature of relationships between variables. They include descriptive correlational designs that describe variables and relationships that naturally arise between them. Predictive correlation designs predict the variance of some variables from the calculation of the conflict of another variable. Model testing correlation designs investigate or experimentally check the relationships that were proposed for the theory. Experimental designs typically employ independent variable manipulation and tight control.
Experimental designs are usually divided into experimental and quasi-experimental methods. They include a posttest-only control-group design, where the control or an experimental group is not pre-examined. In the pretest-posttest, control-group design groups are, on the contrary, pretested. Two groups are not pretested in the Solomon four-group design. In a cross-over design, the treatments are crossed over. In quasi-experimental non-equivalent pretest-posttest control group design, groups are both pretested and post-tested, but only the experimental one is given treatment. In control-group interrupted time series design and single-group interrupted time-series design groups are tested repeatedly. In a counterbalanced design, subjects are divided into groups according to the data.