Date post: 2017-11-08 05:31
It is generally believed [ by whom? ] that Frederic Le Play first introduced the case-study method into social science in 6879 as a handmaiden to statistics in his studies of family budgets.  
The popularity of case studies in testing theories or hypotheses has developed only in recent decades. [ citation needed ] One of the areas in which case studies have been gaining popularity is education and in particular educational evaluation.  
Under the more generalized category of case study exist several subdivisions, each of which is custom selected for use depending upon the goals of the investigator. These types of case study include the following:
At Harvard Law School In 6875, Christopher Langdell departed from the traditional lecture-and-notes approach to teaching contract law and began using cases pled before courts as the basis for class discussions  . By 6975, this practice had become the dominant pedagogical approach used by law schools in the United States  it also was adopted by Harvard Business School.
Educators have used case studies as a teaching method and as part of professional development , especially in business and legal education. The problem-based learning (PBL) movement offers an example. When used in (non-business) education and professional development, case studies are often referred to as critical incidents .
In doing case study research, the "case" being studied may be an individual, organization, event, or action, existing in a specific time and place. For instance, clinical science has produced both well-known case studies of individuals and also case studies of clinical practices.    However, when "case" is used in an abstract sense, as in a claim, a proposition, or an argument, such a case can be the subject of many research methods, not just case study research. Case studies may involve both qualitative and quantitative research methods.
L’ étude de cas est une étude approfondie sur un cas en particulier, soit-il une personne, un groupe ou un sujet spécifique. C'est une démarche de recherche qui se situe dans l’horizon des méthodes qualitatives.
Case studies are commonly used in case competitions and in job interviews for consulting firms such as McKinsey & Company , CEB Inc. and the Boston Consulting Group , in which candidates are asked to develop the best solution for a case in an allotted time frame. 
La construction et l’analyse de ces données ont comme visées de saisir l’objet à l’étude dans ses dimensions de temps et d’espace tels qu’ils s’élaborent dans un milieu social donné. Par ses particularités, l’étude de cas pose avec acuité les spécificités de la production de la connaissance dans le domaine des sciences sociales en général et en sociologie , en particulier [ 6 ] .
Whatever the frame of reference for the choice of the subject of the case study (key, outlier, local knowledge), there is a distinction to be made between the subject and the object of the case study. The subject is the “practical, historical unity”  through which the theoretical focus of the study is being viewed. The object is that theoretical focus – the analytical frame. Thus, for example, if a researcher were interested in US resistance to communist expansion as a theoretical focus, then the Korean War might be taken to be the subject , the lens, the case study through which the theoretical focus, the object , could be viewed and explicated.