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UMass Amherst PSYCH 241 - Exam 1 Study Guide

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Exam 1 Study GuideMethods of Inquiry in PsychologyVariables- Variable- a dimension that can take on different values (age, handedness, time, size etc.)- Independent Variable (IV) -variable that the research intentionally manipulates in order to observe its effect on the DV.- Dependent Variable (DV) -measure of behavior used by the researcher to assess the effects (if any) of the IV.- Individual Differences Variable -a characteristic of the subjects treated as if it were an IV (cannot draw causal conclusions)- Secondary Variable -a variable that is not a part of the hypothesis under study.Types of Secondary Variables- Confound secondary variable -variable that has unintentionally co-varied along with the IV causing a threat to internal validity.- Extraneous or random secondary variable -variable that is not directly related to the hypothesis and which the E does not attempt to control (allows to vary at random).- Controlled secondary variable -variable not related to the hypothesis but which E does control, either by holding constant, equating across groups or by matching. Independent Groups Design- Independent Groups Designs -the IV is varied (or manipulated) between sets of different subjects, one set for each level of the IV. - Three Types of Independent Group Designs:1. Random Groups Design2. Matched Groups Design3. Natural Groups DesignImportance of Random Assignment- Will, on average, in the long run, have an equal representation of all levels of secondary variables in all groups.- The larger the population size and/or the more homogeneous the population, the better randomization will work to provide equal groups.Matched Groups Design- Different subjects serve at the different levels of the IV however the subjects are matchedon the basis of some “important” secondary variable.- An attempt to create equivalent groups when you cannot gather a large number of participants and/or your population is very heterogeneous (with respect to your DV).Natural Groups Design- There is no true IV.- The variable of interest is an “individual differences” variable.- Even if you find a “statistically significant” result, you cannot claim causality.Repeated Measures Design- Researcher’s point of view: the same set of subjects serves at all levels of the IV. Each subject is measured at each level of the IV. - Repeated measures designs are very powerful. - Because subjects are measured repeatedly, there are potential issues of co-varying time-related secondary variables (threats to internal validity), commonly called “order effects” or “carry-over effects”.- The most common order effects are: practice, boredom, and fatigue.- You cannot eliminate these order effects but you can “balance” them across levels of yourIV (counterbalancing)Incomplete Repeated Measures Design- The same set of subjects is measured at all levels of the IV (repeated measures) but each subject experiences and is measured at each level of the IV only once (only one trial at each level of the IV).- Counterbalancing -Controlling time-related variables that are potential threats to internal validity in incomplete repeated measures designs is easy for a two-level IV (AB(1/2) and BA(1/2))- Three-level IV- 6 possible orders and Four-level IV is 24 possible- Latin Square -an arrangement of symbols in rows and columns such that each symbol occurs only once in each row and each column.Complete Repeated Measures Design- The same set of subjects is measured at all levels of the IV (repeated measures) but each subject experiences and is measured at each level of the IV more than once.- Block randomization each block involves one occurrence of each level of the IV.The order of the levels in each block is randomly arranged. (hence, “block randomization”)Advantages of Repeated Measures over Independent Groups Design1. Uses fewer subjects. More economical.2. Controls for all individual differences variables3. Statistically more powerful. More likely to be able to “correctly reject a false null hypothesis” or more likely to be able to accurately detect a true effect of the IV.Disadvantages of Repeated Measures- Must deal with order effects. Usually use counterbalancing which takes time.- You cannot study some variables as repeated measures manipulations. Any variable that causes a permanent or semi-permanent change in the subjects cannot be studied as a repeated measures variable.Internal vs. External Validity- Internal Validity -the degree to which differences in performance (the dependent variable) can be attributed unambiguously to an effect of the independent variable. - External Validity -the extent to which the results of a particular research study can be generalized to different populations, settings, and conditions.Deduction vs. Induction- Deduction -to derive as a conclusion from something known or assumed (to go from a general statement or theory to specific predictions/observations)- Induction -to assert or establish on the basis of observation of particular (specific) facts (to go from specific observations to more general theory or statement)- Deductive Research-the researcher uses already established theories to deduce a specificand testable hypothesis of the form “I expect this will happen if…”- Inductive Research-the researcher gathers many specific findings (usually though performing multiple studies) and then uses these specific findings to create a more general explanation (a theory). “I wonder what will happen if…”Theory Driven Research1. Finding an interesting topic2. Developing a Testable Hypothesis3. Selecting a design and evaluatingethics4. Implement study in a way thatachieves unambiguous results5. Collect and Summarize Data6. Draw conclusions using InferentialStatistics7. Reject, Modify, Support- Graham Wallas (1858-1932)- Four Stages of the Scientific Method:1. Preparation- Doing research, can take years2. Incubation- let is sit, some go sailing3. Illumination- Idea comes to you4. Verification- Experiment- A theory explains events in general terms, while a hypothesis makes a specific statementabout a specified set of circumstances.- Co-variation of events-when one changes, the other changes in a consistent way. - Time-order relationship- one event always precedes the other. Antecedent-consequent.- elimination of plausible alternative causes- eliminate all “threats to internal validity”True Experimental Design- “True” experiment: involves the


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