Study Guide Wednesday November 12 2014 9 16 PM Be familiar with the experimental design What are the two important elements of an experiment i e taking action and observing the consequences Pretesting and post testing Taking action independent variable Consequences dependent variable s change An experiment is a process of observation to be carried out in a situation expressly brought about for that purpose These are all part of the Experimental Model the most powerful research design we have Social science experiments also involve attempting to control the conditions under which the experiment is conducted Know the scientific experiment notation X treatment independent variable Y outcome dependent variable Z rival causal factor O Observation measurement of dependent variable E Equivalence randomization or matching 1 2 Time points Y O Z E X 1 2 Be familiar with the three major pairs of components in the classical experiment Be able to apply define and apply the three components 1 Independent and dependent variables a b Independent variable X treatment Dependent variable Y outcome process or topic being studied for change 2 Pretesting and post testing a b c Studied and tested initially for DV before association with IV IV exposure Remeasured in terms of IV Experimental and control groups 3 Be able to differentiate between experimental and control groups Experimental grouped IV associated Control group pretested and posttested without association of IV If we see a difference we want to make sure it is due to the IV and not to a difference between the two groups What is the relationship between experimental designs and causal inference Experimental design ensures what Randomization eliminates the potential for systematic bias in selecting subjects but subjects may be chosen in other ways that threaten validity The classical experiment with random assignment of subjects guards against most of the threats to internal invalidity The classical experiment may be modified to suit specific research purposes by changing the number of experimental and control groups the number and types of experimental stimuli and the number of pretest or posttest measurements Be familiar with the various kinds of threats to internal validity Internal invalidity can be avoided through the careful administration of a controlled experimental design Internal Validity refers to the possibility that conclusions drawn from experimental results may not accurately reflect what went on in the experiment itself Historical events may occur during the course of the experiment that confound the experimental S G Page 1 Historical events may occur during the course of the experiment that confound the experimental results Subjects change their behavior in the middle of the experiment because of a celebrities behavior Maturation People are continually growing and changing whether in an experiment or not and those changes affect the results of the experiment Testing Often the process of testing and retesting influences people s behavior and thereby confounds the experimental results subjects preoccupation with the questionnaires themselves might influence their responses Instrumentation If we use different measures of the dependent variable say different questionnaires about alcohol use how can we be sure that they are comparable when different questionnaires cause results to differ What is the relationship between samples and populations Why do researchers rely on samples What is a sample What is a population Sampling a procedure used in research by which a select subunit of a populations is studied in order to analyze and entire population Sampling is much less expensive than surveying an entire population It s easier to maintain and deal with subsamples than the entire population Researchers often are unable to conduct research on an entire population We therefore rely on samples Samples are drawn from populations We can them make generalizations for the entire population Be familiar with the following sampling terminology variable parameter statistic and sampling error Variable Age race education occupation and other variables are often included Parameter the value for a given variable in a population The average income of all families in a city and the age distribution of the city s population are parameters The value of a given variable in a population is known as a Statistic The summary description of a given variable in the sample is called a sample statistic Sample statistics are used to make estimates of population parameters The summary description of a given variable is known as a Sampling Error estimating how closely the sample statistics are clustered around the true value where s is the standard error Be familiar with the two main types of sampling methods Be able to differentiate between nonrandom and random samples Random Simple Random Stratified Random Systematic Multistage Cluster Nonrandom Quota Purposive Snowball Random Samples give each member of the population an equal opportunity to be included in the sample Sample Random Samples SRS where each element in the population has an equal probability of being selected Proportionate where you divide the population into strata in order to ensure that the proportion of certain characteristics in the sample are identical to the proportion in the population Disproportionate where you over sample certain groups in order to have enough cases for meaningful comparison with other groups What are some of the purposes surveys serve What are the weaknesses of surveys S G Page 2 What are some of the purposes surveys serve What are the weaknesses of surveys o Purposes o Weaknesses Descriptive survey research uses statistical probability to ask whether something that is true of the sample is true of the population Analytic survey research attempts to address issues of cause and effect Surveys do not measure directly observed behavior but rather attitudes or claimed behavior Not always completely accurate What are the two types of survey design questions used in research What are the strengths and weaknesses of the two types of survey design questions o Two Types of questions Close ended Structured fixed response Strength easy to code and easier for respondents to answer Weakness Lack of detail Open ended Non structured Strength detailed answer Weakness Hard to code and irrelevant answers Be familiar with the two different methods of obtaining data in field research o o
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