Overtime Comparative Case Studies have been constructed, and it has been emphasized that comparison across different contexts should be made. Comparative Case Studies are preferably used in such cases where experimental design is not feasible to use or where there is a need of understanding and explaining how features of the issue within the specific context can influence success or failure of the program (Goodrick, 2014).Comparative Case Studies consists of analysis and constructions of difference and similarities and other patterns among two or more cases that have an aligned goal or focus. Mostly both qualitative and quantitative data are included in a Comparative Case Study. It, however, focuses on the generation or creation of a good understanding of the context and cases. Methods such as interviews, fieldwork visits, document analysis, and observations are commonly used and such them data collection is employed (Goodrick, 2014).AdvantagesRelative to formal and statistical models Case Study Methods have been seen to be of comparative advantage (Goodrick, 2014). Some of the most prominent advantages are a better historical explanation, heuristic identification of hypotheses and new variables, measurement and operationalization of qualitative variables, complex relations incorporation such as path dependency and equality, and the ability to examine potential mechanisms in particular cases or particular contexts.LimitationsDespite the numerous advantages case study methods also have some limitations in some contexts (Goodrick, 2014). To deploy this method of study a person must have a range of expertise and skills. It is really important to match and assess the team against the required skills. Comparative case studies are seen to have been resources hungry because of the extensive and intensive fieldwork required. However, in some cases, the case study can be entirely based on secondary data, and there will be no need for collection of primary data. But in these cases, the quality of the data must be suitable. If there is too much of lag between the cases, then the findings can be considered as less reliable.Single-Case Research DesignsSingle-Case Research Designs which are also known as the single-subject design is a method of evaluation that is used to test the success of a treatment or an intervention for a particular case. The case could be a community, a person or school or anything for that matter. It helps to provide evidence regarding the effectiveness of a proposed intervention. However, the sample size in such cases is taken relatively smaller. Commonly the SCDs make use of visual analysis of data to compare the target behavior of the participants systematically. The target behavior is tested before and after the intervention is given (Willis, 2014). If the data indicates a change in behaviors of the participants, it means the changes occurred due to the intervention. But to have evidence or proof it was caused by the intervention replication of the process is done and then it is checked whether or not the results could be replicated.AdvantagesOne of the many advantages of using SSRD is that the study focuses more on how an individual subject uniquely responds to the factors of the experiment rather than making a full-fledged comparison of how many individuals responded to the factors of the experiment and how much did not (Willis, 2014). SSRD allows the researchers to conduct their research rapidly without having to look for and man so many suitable participants who could be time-consuming.LimitationsAlthough in this method a researcher does not have to have a large number of participants for the study, it has also had drawbacks which state that since the findings have been collected from a single participants, therefore, they are not applicable over a general population as the data from one person cannot be generalized. All the test or the trial shows us is what happens to an individual subject rather than telling us about the phenomenon of a large number of participants.Counterfactual Impact EvaluationCounterfactual impact evaluation is a technique of comparison that involves comparison of the outcomes that arose from a program or a policy made and tested. However, there are two groups involved in this study. One is the control group or comparison group which is not tested, or the policy or program is not applied to them. The other is treated, or experiment group which is a test or the policy or program is applied to them. Such kind of study enables you to study the effects of policy easily by comparing the behavior of the treated and the control group. The comparison provides us with the information that what were the real causes that brought such and such changes in the experiment group. The case for counterfactual effect assessment depends on the need to gather confirm and decide if arrangement targets have been met and, eventually, regardless of whether the assets were utilized effectively. These answers input into the plan and usage of future intercessions and budgetary choices. In light of this, the European Commission is focused on having effect assessment part of a strategy execution life-cycle.DecisionFor a researcher, the preferred choice in this regard is a single case study. This might be especially suitable for those marvels that are just less manageable to more shallow measures and tests (or to be sure any substantive type of evaluation) and also those for which our explanations behind comprehension or potentially clarifying them are unchangeably subjective as with huge numbers of the regularizing and moral issues related to the act of global relations (Gustafsson, 2017). From different epistemological and systematic viewpoints, single contextual investigation examination can join both idiographic sui generis cases and, where the potential for speculation may exist, nomothetic contextual investigations reasonable for the testing and working of causal theories. At last, it ought not to be disregarded that a flag preferred standpoint of the contextual analysis with specific significance to universal relations – additionally exists at a more down to earth instead of the hypothetical level (Gustafsson, 2017).ReferencesGoodrick, D. (2014). Comparative Case Studies: Methodological Briefs-Impact Evaluation No. 9 (No. innpub754).Gustafsson, J. (2017). Single case studies vs. multiple case studies: A comparative study.Levy, J. S. (2015). Counterfactuals, causal inference, and historical analysis. Security Studies, 24(3), 378-402.Willis, B. (2014). The advantages and limitations of single case study analysis. E-International Relations.