Abnormal Psychology, the science and treatment of psychological disorders by A. M. Kring, S. L. Johnson, G. C. Davison and J. M. Neale (thirteenth edition) – Chapter 4

The goal of exploratory research is to disprove hypotheses, generate hypotheses and getting rich descriptions. Qualitative research is primarily exploratory research. The limitations of qualitative research are generalizability (1), causality (2) and biases (3). The solution to the problem of generalizability is using correlational studies. The solution to the problem of causality is conducting experiments and longitudinal studies.

The case study involves recording detailed information about one person at a time. One major pitfall of case studies is the bias of the theoretical framework. Correlational studies are used to study prevalence, risk factors and incidence. Limitations of correlational studies are the representativeness of samples and that confidence intervals are rarely given. There is always the possibility of a third-variable mediator in correlational studies.

There are several correlational methods for behaviour and molecular genetics:

1. Family method
   Studying a genetic predisposition among members of a family
2. Twin method
   Studying the presence of disorders in twins
3. Adoptees method
   Study differences between adopted children and their biological parents
4. Association study
   Study the relationship between a specific allele and a trait or behaviour in the population
5. Genome-wide association studies (GWAS)
   Association studies using all genes

Experiments are used to test causality. Internal validity is important for experiments and there is relatively low external validity. In analogue studies, the researcher attempts to emulate the conditions hypothesised to lead to abnormalities. Randomized controlled trials are studies in which clients are randomly assigned to receive active treatment or a comparison. Treatment outcome research addresses the question of whether the treatment works. A single-case experimental design is an experiment involving one person responding to manipulations of the independent variable. The reversal design or the ABAB design is one form of single-case experimental design:

A) Initial period (baseline)
B) Treatment
A) Reinstatement of conditions of baseline
B) Reintroduction of treatment

Clinical significance is defined by whether a relationship between variables is large enough to matter. The efficacy of treatment refers to whether the treatment works in the purest of conditions. The effectiveness of treatment refers to whether the treatment works in the real world.