A research design typically outlines the theories and models underlying a project; the research question(s) of a project; a strategy for gathering data and information; and a strategy for producing answers from the data.
Fixed designs are normally theory-driven; otherwise, it is impossible to know in advance which variables need to be controlled and measured.
One reason for using a flexible research design can be that the variable of interest is not quantitatively measurable, such as culture.
In a typical experimental study, there will be at least one "experimental" condition (e.g., "treatment") and one "control" condition ("no treatment"), but the appropriate method of grouping may depend on factors such as the duration of measurement phase and participant characteristics: Confirmatory research tests a priori hypotheses — outcome predictions that are made before the measurement phase begins.
The reason for this is that in confirmatory research, one ideally strives to reduce the probability of falsely reporting a coincidental result as meaningful.
Exploratory research, on the other hand, seeks to generate a posteriori hypotheses by examining a data-set and looking for potential relations between variables.
If the researcher does not have any specific hypotheses beforehand, the study is exploratory with respect to the variables in question (although it might be confirmatory for others).
The advantage of exploratory research is that it is easier to make new discoveries due to the less stringent methodological restrictions.
Research designs such as repeated measurements and longitudinal study are needed to address process problems.
First of all, it is necessary to think of the best way to operationalize the variables that will be measured, as well as which statistical methods would be most appropriate to answer the research question.
[8] Additionally, many researchers employ power analysis before they conduct an experiment, in order to determine how large the sample must be to find an effect of a given size with a given design at the desired probability of making a Type I or Type II error.
Non-experimental research designs do not involve a manipulation of the situation, circumstances or experience of the participants.