Answer to Question 1
Experimental, correlational, or single-participant methods vary depending on the research strategy used. The different research strategies include: Survey, longitudinal, and historical research; twin studies, treatment outcome, treatment process, and program evaluation studies. Survey research allows for the collection of data from all or part of a population to assess the relative prevalence, distribution, and interrelationships of different phenomena. Longitudinal research examines behaviors over a long period of time. Historical research reconstructs the past by reviewing data from historical documents. Twin studies are generally used to evaluate the influence of heredity and environment. Treatment outcome studies helps answer the question of whether treatment is effective. Treatment process studies focuses on how or why treatment is effective. Program evaluation studies analyze the effectiveness of an intervention or prevention program. It is common for researchers to combine elements of different methods in their research, such as a treatment outcome study utilizing both surveys and longitudinal strategies to gather information.
These strategies are used to determine the extent of mental disturbance found in a targeted population and the factors that influence the rate of mental disturbance. Prevalence and incidence describe the rates of mental disturbance. Prevalence rate is the percentage of individuals in a targeted population who have a particular disorder during a specific period of time. Incidence rate is the number of new cases of a disorder that appear in an identified population within a specified time period.
Answer to Question 2
Psychologists use the scientific method in their approach to understanding human cognitive, affective, and behavioral processes. Research must have the potential for self-correction, clear hypotheses about the relationships among variables studied, use of clear operational definitions of variables being studied, reliability and validity of instruments used to measure the variables being studied, and an acknowledgment of base rates.
Among the many research designs used by psychologists are experiments; correlational studies; analogue, field, and single-participant studies; biological research strategies; and epidemiological research. The experiment is the only way to determine a cause-and-effect relationship between any given event and a particular behavior. Among the obstacles encountered in using experiments is the ability to control potentially confounding variables (i.e., extraneous factors other than those being studied that may affect the outcome of the experiment). One way to overcome this is to conduct research in a laboratory; however, that creates a problem of generalizability, or external validitythat the findings from the laboratory may not be applicable to the real world. Control groups (research participants who are similar to participants in the experimental group in all ways except for the manipulation of the independent variable) would be used to eliminate the question of whether a positive outcome resulted from the intervention itself or from other intervening variables (such as passage of time or the placebo effect). Placebo groups (who are told they are receiving a treatment that will have a particular effect) may be used to overcome concerns that the experimental group improved due to expectancy effectsi.e., believing the treatment they are getting will have an effect. Expectancy effects are also reduced through blind studies in which the participants are not aware of the experimental conditions, or a double-blind study in which individuals working directly with the participants are also unaware of the experimental conditions.
It is not always ethical or practical to conduct research with humans. One way around this is by using correlational studies to look at the extent to which one variable increases or decreases in relation to other variables. A major drawback of correlational studies is that they cannot tell us anything about cause and effect, merely the strength of the relationship between variables. Analogue studies are another strategy for dealing with ethical or practical limitations of experiments. Under controlled conditions, these studies try to simulate real life, using rats, students, or other convenient participants in place of the actual population to which an intervention would be applied. To overcome the problems that analogue studies may present by being contrived rather than applied to real life situations, highly trained researchers sometimes use field studies in which behaviors and events are observed and recorded in a natural environment. However, limitations include difficulty determining causality, an overwhelming number of uncontrollable variables, and the potential for the observed behavior to be influenced by the presence of the researchers. Case studies and single-participant experiments are used to examine rare or unusual phenomena or to test specific treatments, but findings from these studies are not generalizable to larger populations. However, the findings can generate useful hypotheses to be tested on larger groups. Genetic linkage studies look for genetic patterns, but are limited by changing diagnostic criteria and accuracy of family reporting, which is often remedied by using multiple informants. Epidemiological research examines the rate and distribution of mental disorders in a population and can offer insight into what groups are at risk for certain disorders and what factors might influence the prevalence and incidence of particular disorders. Such large studies are expensive and apply to groups, not necessarily individuals.
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