In this blog I will be describing case studies and single case designs, and discussing the differences between them.
A single case design is basically one where the subject serves as their own control group. They’re used more often to see how effective interventions are, as we’ve seen in our behavioural lectures. In a single-subject design, there are three phases. The first is the baseline phase. This phase is where the subject is measured on their behaviour with no interventions or behaviour changes taken. The next stage is the intervention stage. This is where the subject is measured on their behaviour when the independent variable has been introduced. The final stage is the reversal stage. This is where the independent variable is removed again. The researcher should only move onto the next stage when the data is stable, so stronger results are found. Single case designs are often used because they’re far more sensitive to individual differences than cases with more than one participants.
A case study is an analysis of a single unit. It is not necessarily on just an individual person, it can also on a specific group of people or on an event. In a case study, researchers collect detailed information about the subject. An advantage of case studies is that they give very detailed information, which is sometimes on very unique and interesting cases. An example of this kind of case study would be David Reimer, who was born as a male but was raised female due to an accident in a routine circumcision. A disadvantage of case studies is that they are very subjective, both because they are only on an individual unit and also because of the researchers. Another problem is that it is hard to generalise from case studies, as they are only one person and so you can’t apply the results to the general population.
There is a big difference between case studies and single case designs, despite them superficially sounding similar. In a single case design, the researcher has much more control over the participant. They introduce an independent variable and measure the behaviour, so this allows cause and effect to be more readily established. Case studies, on the other hand, the researcher simply observes the behaviour. This means that they are not very effective at testing theories. One effective way of utilizing both designs is using a case study to initially research an unknown area, and then using single case studies to test the hypothesis more effectively.
So overall, case studies and single case designs are two different kinds of experiment design that use individuals as subjects. They both have their advantages and disadvantages, and can be effectively used in different cases.
Numbers and Psychology 
st92
/ April 17, 2012I agree that they both have their advantages and disadvantages. I think it’s still important that both methods are used, though, and we don’t rely on single-case designs simply because they appear more ‘scientific’. Although case studies have problems with being generalised, due to their ability to provide lots of in-depth knowledge researchers can create and test a hypothesis, because the case study has shown what may be important for future research.
psuc46
/ April 18, 2012You have made clear points and have defined and explained the question well. They both have their advantages and disadvantages and need to be used depending on the situation. You could have used a little more research in your blog, for example you could have used a study to explain further what a case study and single case design was. The case of Phineas Gage is a good example of a case study design (Harlow, 1848). Apart from that I really enjoyed reading your blog, great job!
References: Harlow, John Martyn (1848). “Passage of an iron rod through the head”. Boston Medical and Surgical Journal 39: 389–393