Exam 2 Review Sheet Chapters 6 10 Causation and Experimental Design Chapter 6 Experimental Designs o 3 common elements 5 criteria of causation 1 At least 2 comparison groups experimental control 2 Random assignment solves a lot of problems in experimental designs creates equal groups require large samples no characteristic which places individual in one group over the other Roughly same age gender major etc 3 Stimulus change applying some variable that you ve changed or application of a program etc o Cause an explanation for some characteristic attitude or behavior of groups individuals or other entities such as families organizations or cities or for events o Causal effect When variation in one phenomenon an independent variable leads to or results on average in variation in another phenomenon the dependent variable o 1 Empirical Association o 2 Appropriate time order o 3 Non spuriousness A relationship between 2 variables that is not due to variation in a 3rd variable variation in an IV causes variation in a DV A criterion for establishing a causal relationship between two variables when a relationship between two variables is not due to variation in a third variable Spurious relationship A relationship between two variables that is due to variation in a third variable o 4 Identifying a causal mechanism Many social scientist believe that a causal explanation is not adequate until a causal mechanism is identified What process or mechanism is responsible for the relationship between the IV DV Mechanism Some discernible means of creating a connection A discernible process that creates a causal connection between two variables o Time order Time order A criterion for establishing a causal relationship between two variables The variation in the independent variable must occur before the variation in the dependent variable o 5 Specifying the context in which the effect occurs Context A focus on idiographic causal explanation A particular out come is understood as part of a larger set of interrelated circumstances Contextual Effect Relationships among variables that vary among Cross sectional vs longitudinal designs geographic units or other social settings o Cross sectional study in which data are collected at only one point in time snap shot most common form of analysis simplest cheapest but cannot fully capture change implying causal direction but can t say for sure findings are consistent over time o Longitudinal A study in which data are collected that can be ordered in time also defined as research in which data are collected at two or more points in time measures characteristics at multiple time points more powerful for measuring change more costly difficult o Association Necessary criterion for establishing a causal effect A change in the independent variable is correlated with a change in the dependent variable if there is no association between the 2 variables there cannot be a causal relationship o Cohort People who all have experienced a similar event or common starting point Event based design cohort study follow up samples are collected at one or more times from the same cohort Birth cohorts Those who share a common period of birth ex Those Seniority cohorts Those who have worked at the same place for about born in the 1950s 5 yrs about 10 yrs and so on School cohorts Freshman Sophomores Juniors Seniors o Cohort Study aka event based design type of panel study in criminology A type of longitudinal study in which data are collected at two or more points in time from individuals in a cohort Panel study but w a group of people that shared some experience at the same time o Case study following one single person over time or very few cases qualitative research direct observation spending a lot of time w one person Wholistic view of each case incorporates time but not in the systematic precise timed way as quantitative research True experiments An experiment in which subjects are assigned randomly to an experimental group that receives the treatment or other manipulation of the independent variable and a comparison group that does not receive the treatment Outcomes are measured in a post test o Elements of a true experiment Has an experimental group control group is done over time compare both post tests then if we have a pre test we look at it there was a change in both groups why Without a pretest no way of knowing what caused the change rate of change sees which group changed more o Pre test and post test Pre test Same as the post test but administered at an earlier time A true experiment does not require a pre test In experimental research this is the measurement of an outcome dependent variable prior to an experimental intervention or treatment independent variable Examines differences in groups not necessary but desirable don t really need it because they should be equal to start w if correctly randomly assigned but we use them to measure change tests randomness and examines conditions under which the stimulus had an impact whether certain kinds of people responded different to the stimulus Post test In experimental research this is the measurement of an outcome dependent variable after an experimental intervention or treatment independent variable after intervention measures differences o Experimental vs control group Experimental In an experiment the group of subjects that receives the treatment or experimental manipulation Control In an experiment or study a comparison group that receives no treatment o Random assignment randomization A procedure by which each experimental subject is placed in a group randomly Useful for ensuring internal validity not generalizability Matching A procedure for equating the characteristics of individuals in different comparison groups in an experiment Problem poor replacement for randomization individuals can be matched only on a few characteristics so unmatched unknown differences between the experimental control group may influence outcomes Ceteris Paribus Latin phrase meaning other things being equal Quasi experimental designs A research design in which there is a comparison group that is comparable to the experimental group in critical ways but subjects are not randomly assigned to the comparison and experimental groups Done when we can t do a true experiment o Field experiments A study conducted in a real world setting o Non equivalent control group designs A quasi experimental design in which there are experimental and
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