Part 2 of Chapter 2 - Designing an Experiment

Designing An Experiment: experimental + contra groups: experimental group-participants thai experience the manipulated variable → group designed to answer the research question control group: participants that do not experience the manipulated variable -basis for comparison + controls for anance factors that might influence the results Ót tha stuay only difference between expenment + Control groups is experimental manipulation Defining Varlables and How they will be measured: operational definition: descriptions of what actons + operations will be used to measure the dependent variables + manipulate the independent- variables Avoiding Bias + The Placebo Effect Experimenter Bias: rescarcher expectations skew the results of the study participant bias: participant expectations skew tve results of the stuay Single-bund Study: experiment in which the researcher knows which participants are in the experimental group but participanis do not a controis participant expectations dovible blind study: experiment in which both the researchers and participants are blind to grap assignments controls botn participant i experimenter expectations Placebo Effect : people's expectations or bellefs influencing or determining their experience in a given situation Variables independent variable: variable thatis infivenced/controlled by the experimenter. Ideally this should be the only imporzant differance between the experimental and control group dependant vanable: Variable that the researcher measures to see how much effect tue independent variable nad * independent vanable changes dependent variable * Selecting Participants participants : subjects of psychological researon population is too big, so you use a sample Sample: subset of individuals selected from larger population population: Overall group of malviduals that tue researcher is interested in random sample; subset of a larger population in which every member of the population has an equal chance of being selected preferred sampling be i is more likery the selected participants will be representative of the larger population Assigning participants to groups: experimental or control Random Assignment: method of experimental group assignment in which all participants have an equal chance of being assigned to either group achieved using statistical software or by flipping a coin a prevents systematic differences betrueen groups (gender /age) Without random assignment, experiment cant find true cause i effect reiahonship Issues to consider Manipulating Variables: random assignment is required to state causation, once randomly assigned each group is somonow manipulated. however, some expenmental designs are more complicated Ethics: some questions cannot be answered using an experimental design because they would be unethical Interpreting Experimental Findings once data has been collected, a statistical analysis is conducted Statistical analysis: determines how likely any difference between experimental groups is due to chance • psychologists usually discuss results as significant or non-significant if the odds that the differences occured by chance are 5% or less, then the results are significan+ a true expenment, including random assignment, manipulation of the independent variable and control of extraneous variables reduce the odds of results occuring by chance Reporting Findings research is usually reported in scientific journals -aimed @ professionals/scholars → articles publisted for prer-reviewed joumal articles peer -reulewed joumal articles: article read by several other scientists (usually anonymously) wI expertise in the subject matter, who provide feed back regarding the quality of the manuscript before it is accepted for publication helps weed out poorly conceived or executed studies improves articles wi suggested revisions determines whether the rescarch is described clearly enough to be replicated by other researchers replication: - determines reliablity of original rescaron design - can include adaitional measures that expand on the original findings • provide more eudence to support the original finding or to cast doubt on those findings Reliability + Validity: Reliability • consistency + reproducibility of a given result • would the same test give the same result? • do the instruments/1001s used to callect data do so in consistent, reproducible ways -when multiple people mare observations in astudy. they need to do so and record them in the same way inter-rater reliability; measure of agreement among doservers on how they record + classify a particular event a reliable, consistent measurement doesnit always mean that it is measuring something correcHy Validity: accuracy of a given result in measuring what it is designed to measure Li does a test measure what it's supposed to measure? Valid measure = reilable BUT reliable measure I Valid Ethics: research invaiving human participants • research involving human participants must adhere to strict guidelines institutional review board CiRB): committee of administrators, Scientists, and community members that reviews proposals for research involving human participants exist @ any research institution that receives federal Support for researen invaluing human participants IRB mus+ approve research proposal informed consent; process of informing a research participant about runat to expect during an experiment + then obtaining the person's consent to participate Inciudes : - potential risks involve - Implications of the research - notification that the participation is voluntary - notification that any data collecied will be confidential Deception • Sometimes deception is necessary to prevent the participants knonedge of the rescaron question affecting the results as long as it's not harmful deception: purposely misleading experimental participants in order to maintain tue integrity of the experiment debriefing: when an experiment involued deception, participants are told to complete and trutnful information about the experiment @ its conclusion Ethics: research involuing animal subjects - 90%0 of psychological research involves animal subjects (rodents/birds) -animals make good subjects be they have simlar basic processes as humans - animals used when research is unethical to humans -researchers must aim to minimize pain/distress Institutional animal care + use committee : Committee of administrators, scientists, vetinerians and community members that reviews proposals for research invaluing non-human animars