Research Methods Study Guide 3 Step 1 Be able to answer ALL of the Check Your Understanding Questions from the Chapters covered in this book Chapter 10 Introduction to Simple Experiments Be able to recognize if an experiment meets criteria for establishing causation o Covariance is the casual variable related to the effect variable That is are the levels of the independent variable associated with distinct levels of the dependent variable o Temporal precedence does the causal variable come before the effect variable in time o Internal validity are there alternative explanations for the results What is a matched group design o The simplest type of random assignment Researchers assign participants at random to one condition or another of their experiments Assigning people by gpa in order like the chart with the green people What is the difference between within subject design and between subject design o Between Subject Design Aka Independent groups design Different groups of participants are exposed to different levels of the independent variable o Within Subject Design Aka Within groups design all participants are exposed to all levels of the independent variable o What are the advantages disadvantages of each WITHIN subject designs Advantages Reduces error variance due to individual differences among subjects across treatment groups Effects of independent variable are more likely to be detected Requires fewer participants WITHIN subject designs Disadvantages More demands put on participants longer study more complicated study may increase drop out rate When participants do drop out all their data is unusable Mistakes more costly again because you lose a large amount of data Carry over effects BETWEEN subject designs Advantages BETWEEN subject designs Disadvantages What is carryover and what are the six different types of carryover effects for within subject designs o Carryover effects exposure to a previous treatment affects performance in a subsequent treatment called order effects Learning Learning a task in the first treatment may affect performance in the second irrespective of IV Fatigue Earlier treatments may affect performance in later treatments because participants will get tired Habituation Repeated exposure to a stimulus may lead to unresponsiveness Sensitization Exposure to a stimulus may make a subject respond more Contrast Participants will compare the current treatment to treatments that to that stimulus strongly to another came before Adaptation Physiological changes over time based on experimental setting What are potential ways to deal with carryover effects READ o Counterbalancing o Try to minimize carryover effects o Introduce breaks into the study to allow effect of previous treatment to wear off o Practice trials to let participants get used to the new treatment and forget about old treatment o Treatment order as an independent variable o If you have enough participants in your study you can include treatment order as an independent variable in your analysis o Will let you know if significant carryover effects are present in your study o What different methods are there of counterbalancing and what are the advantages disadvantages of each Complete Counterbalancing Advantage All possible combinations of treatments are represented Disadvantage Minimum number of subjects can get large fast K K factorial 3 conditions 3 X 2 X 1 6 subjects needed 5 conditions 5 X 4 X 3 X 2 X 1 120 subjects needed Partial Counterbalancing Includes only some of the possible treatment orders Advantage Attempts to counter learning effects and fatigue effects Disadvantages Won t counter effect of each treatments on each other Random Order Counterbalancing Assign random order of treatment for each Carry over effects may not completely balance but are randomly distributed Likelihood of treatment effects being the result of carryover effects small but treatments participant across treatments possible o What is a Latin square design and how is it useful Don t have to calculate Way to make sure you have every condition coming before or after each condition reduce carry over when you have a high number of conditions A counterbalancing procedure that ensures each condition precedes or follows each other condition at least once Controls for ordinal position of each treatment Each condition precedes or follows each other condition once Chapter 11 More on Experiments Confounding and Obscuring Variables Be able to describe the multiple threats to internal validity in class You won t need to list define them but you ll need to identify them and or be able to know the differences among them o History o Maturation o Testing o Practice Effect Events that occur between the DV measurements in a repeated measures design pretest posttest Changes in participants that occur over time during an experiment These changes could include actual physical maturation or tiredness boredom hunger and so on Because measuring the DV causes a change in the DV A practice effect is a beneficial effect on a DV measurement caused by previous experience with the DV o Reactive measures DV measurements that actually change the DV being measured o Instrumentation Instrument Decay When the equipment or human measuring the DV changes the measuring criterion over time o Regression o Selection Originates with statistical concept called regression toward the mean Equivalence If we choose participants in such a way that our groups are not equal before the experiment we cannot be certain that our IV caused any difference we observe after the experiment o Attrition Mortality Mortality can occur if experimental participants from different groups drop out of the experiment at different rates o Diffusion or Imitation of Treatments Occur if participants in one treatment group become familiar with the treatment of another group and copy that treatment o Ex You are unable to use data from 20 of the participants you recruited because they got sick and were unable to complete the second phase of your data collection Is this a problem of history maturation attrition or regression maturation How does generalizability relate to problems associated with external validity o Results not being able to be used outside the testing environment The results cannot be used for everyone Why is it difficult to simultaneously have strong internal AND external validity o Because if you have strong internal validity it won t be as necessarily as strong when
View Full Document
Unlocking...