basic components of a research study hypothesis an educated guess as to what the study might find research design plan for testing hypothesis includes dependent independent variables IV the aspect manipulated or thought to influence the change in the DV i e ecstasy use DV some aspect of the phenomenon that is measured and is expected to be changed or influenced by the IV i e cognitive abilities internal external validity internal extent to which you can be confident that the IV is causing the DV to change external extent to which the results of the study can be generalized applied outside the immediate study testability the ability to support the hypothesis can this hypothesis be proved or disproved through the experiment confounding variable a variable besides the IV that may also affect the DV this makes the results uninterpretable 3 methods to ensure internal validity 1 having a control group in a control group people are similar to the experimental group in every way except that they are not exposed to the IV helps rule out alternative explanations for results 2 randomization the process of assigning people to different research groups in such a way that each person has an equal chance of being placed in any group 3 analogue models these create in the controlled conditions of the laboratory aspects that are comparable to the phenomenon under study however controlling all aspects of a study so that only the IV changes makes it so the result is not relevant to the real world for example studying only 25 year old males w college degrees doesn t allow the results to be generalized to other populations so internal and external validity are often inversely related the best solution for achieving internal AND external validity may be to conduct several related studies statistical significance mathematical calculation about the difference btwn groups clinical significance whether the difference was meaningful for those affected for example if the difference between participating in extensive therapy and not participating in extensive therapy only made people stay sober for 2 more days even though this difference may be statistically significant few people would say the therapy was worth it it wasn t meaningful to the people in the study effect size how large are the differences btwn groups how much does each person in the study improve or worsen individual differences patient uniformity myth the tendency to see all participants as one homogenous group leads researchers to make inaccurate generalizations about disorders and their treatments just b c a treatment is statistically significant doesn t mean it will work for every person types of research methods case study intensive investigation of one or more individuals doesn t use scientific method relies on a clinician s observation of differences among one person or group w a disorder ppl w other disorders ppl w no disorders however case studies may lead us to conclude things about the general pop based on one person which we really can t do since case studies have no controls and the results of the study could be unique to that 1 person or could be due to a non obvious combo of factors correlational study seeing if 2 variables are statistically related doesn t manipulate or change conditions but rather studies phenomena just as they occur however there is a problem of directionality which means that we don t know the direction of causality btwn the variables or if a third variable causes both of them epidemiological research a type of correlational research epidemiology is the study of the incidence of new cases during a specific period distribution and consequences of a particular problem or set of problems like disorders in 1 or more pops epidemiologists study the prevalence of disorders helps us understand the course of disorders however can t tell us about what causes a particular phenomenon experiment manipulation introduction or withdrawal of a variable in a way that would not have occurred naturally of an IV and the observation of its effects we manipulate the IV to answer the question of causality group experimental designs observe the effect of an IV on a group of people a special type of group experimental design is a clinical trial which is an experiment used to determine the effectiveness safety of a treatment this method of evaluation follows generally accepted rules about how research participants should be selected how many ppl should be in the study how they should be assigned to groups how the data should be analyzed clinical trials refer to the general category of studies that follow these standards control group people who are similar to the experimental group in every way except they are not exposed to the IV helps us measure success of treatment placebo effect when behavior changes as the result of a person s expectation of change rather than as a result of any manipulation by an experimenter occurs even when a patient is given a real treatment since they expect it to work researchers often use placebo control groups to make the control group believe they are getting treatment this helps moderate the placebo effect helps distinguish the results of positive expectations from the results of actual treatment a double blind control is a variant of the placebo control group procedure neither the researchers nor the participants know which group they are in what treatment they are receiving this helps eliminate researcher bias comparative treatment research researcher gives diff treatments to 2 or more comparable groups of ppl w a particular disorder assesses how or whether each treatment helped the people who received it treatment process finding out why or how your treatment works treatment outcome finding out what changes occur after treatment single case experimental designs systematic study of one individual under a variety of experimental conditions popularized by B F Skinner one strategy of single case studies is repeated measurement measuring a behavior several times rather than just once before the IV is changed and once after 3 important parts of repeated measurement are 1 the level or degree of behavior change w different interventions 2 the variability or degree of change over time and 3 the trend or direction of change another strategy is a withdrawal design researcher tries to determine whether the IV is responsible for changes in behavior the 3 parts are 1 a person s condition is evaluated before