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Clinical Research Methods Observation Unsystematic Controlled Case Studies Each has it’s place…but you should be aware of the limitations of each approach. Research Methods in Psychology By asking questions of a representative sample, researchers using the survey method can provide useful information about a much larger population. The wording of the questions can influence participants' responses. Research Methods in Psychology A case study is an in-depth analysis of a single person or event. Although the findings of a case study may apply only to the person who was studied, they may provide direction for further study using other methods. Research Methods in Psychology To study behavior in real-life settings, psychologists often use naturalistic observation. This technique also may suggest research projects using more controlled approaches. In using naturalistic observation, the onlooker must be unobtrusive and avoid influencing the behavior being studied. Correlational Research The correlation technique indicates the degree of association between 2 variables Correlations vary in direction: Positive association: increases in the value of variable 1 are associated with increases in the value of variable 2 Negative association: increases in the value of variable 1 are associated with decreases in the value of variable 2 No relation: values of variable 1 are not related to variable 2 values Correlations Correlations also vary in the strength of the association Zero correlation: no relationship between the 2 variables Strong correlation: knowing the value of one variable permits one to accurately estimate the value of the other variable Strong correlation can be positive or negative Correlations can be seen in scatter plots A Zero Correlation High • • • • • • Dependent • variable • • • • • • • • • • • Low Low Independent variable High A Moderate Positive Correlation High • • • • • • • • • • Dependent variable • • • • • • • • • • • Low Low Independent variable High Correlation Difficulties Research Methods in Psychology Because it can generate cause-and-effect statements, many psychologists believe that the experimental method is the most powerful research approach. By manipulating an independent variable (the cause), the researcher determines whether it influences the dependent variable (the effect). True Experimental Design Manipulate Select Assign to experimental Compare groups stimulus dependent sample variable scores on posttests Pre Post test test Randomize Condition Control Pre Post test test Internal Validity Internal validity in experiments refers to: whether the independent variable actually does produce the effect it appears to have on the dependent variable. E.G. “Does the Rogerian therapy actually reduce anxiety symptoms in participants?” Does the class-room behavioral mgt program actually reduce problem behavior? Threats to Internal Validity Selection - the biases which may result in selection of comparison groups History - the specific events which occur between the first and second measurement Maturation - the processes within subjects which act as a function of the passage of time Instrumentation - the changes in the instrument, observers, or scorers which may produce changes in outcomes Statistical regression - the selection of subjects on the basis of extreme scores or characteristics Mortality: Experimental attrition -the loss of subjects Internal Validity Internal validity means that you have evidence that what you did in the study (i.e., the program) caused what you observed (i.e., the outcome) to happen. The key issue is Causation True Experimental Design overcomes all of the internal validity threats Because subjects are randomized to treatment and control groups, there is no bias/favorites, both groups are equally likely to have same qualities External Validity The capacity to generalize findings to other groups of people and settings. Threats to external validity Selection Bias: Unrepresentative samples Reactive effects of experimental setting Multiple treatment interference Single Case Experimental Design Skinner – Experimental analysis of behavior Much more rigorous than Case studies Establishing a baseline Two types of single case experimental designs: 1. ABAB 2. Multiple-Baseline designs ABAB Baseline – Treatment – Baseline – Treatment Multiple-Baseline Design Home – School - Daycare Single-Case Design X X X X X X X X X Baseline, operant Treatment, Return to rate Reinforcement Baseline, Extinction contingency A B A Multiple Baseline Design Useful in testing for a treatment effect when you believe that the effect is irreversible. Baseline data are collected on: 2 or more behaviors for same individual Same behavior for 2 or more individuals Same behavior across 2 or more situations for the same individual. Multiple Baseline Design A Baseline Treatment Behaviors, B Baseline Baseline Treatment People, or C Baseline Baseline Baseline Treatment situations D Baseline Baseline Baseline Baseline A Baseline CBT Behaviors, B Baseline Baseline CBT People, or C Baseline Baseline Baseline CBT situations D Baseline Baseline Baseline Baseline Dependent variable might be anxiety ratings Epidemiological Research Definition: the study of the incidence, prevalence and distribution of illness/disease in a given population Incidence: the number of new cases of a disease during a given time interval, usually one year. It can be expressed as a proportion or as a rate. Prevalence:the total number of cases of the disease in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population. Epidemiology The Greek physician Hippocrates is usually said to be the "father of epidemiology". He is the first person known to have examined the relationships between the occurrence of disease and environmental influences. He coined the terms endemic (for diseases usually found in some places but not in others) and epidemic (for disease that are seen at some times but not others. Epidemiology Does not definitively establish causal relationships, but may still lead to preventative measures to stop the spread of disease Dr. John Snow is famous for the suppression of an 1854 outbreak of cholera in London's Soho district. He identified the cause of the outbreak as a public water pump on Broad Street and had the handle removed, thus ending the outbreak. This has been perceived as a major event in the history of public health and can be regarded as the founding event of the science of epidemiology.
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