# Shared Flashcard Set

## Details

Stat 1200
N/A
54
Mathematics
Not Applicable
02/21/2010

Term
 Population
Definition
 collection of all units of potential interest
Term
 Sample
Definition
 collection of units upon which we actually take measurements
Term
 Survey
Definition
Term
 Random experiment
Definition
 assigning people randomly to one of two groups
Term
 Random assignments
Definition
 Ex. giving one group an active drug and other group a placebo
Term
 Observational Study
Definition
Term
 7 components of a good study
Definition
 SOURCE, RESEARCHERS, INDIVIDUALS OR OBJECTS STUDIED, MEASUREMENTS,SETTING, EXTRANEOUS DIFFERENCES, MAGNITUDE.
Term
 categorical variables
Definition
 (aka qualitative variables) those that divide subjects into groups, BUT dont allow mathematical operations to be performed.
Term
 Measurement variables
Definition
 (aka quantitative variables)those for which the responses are meaningful numeric values.
Term
 nominal variables
Definition
 categorical variables that have no nature order (ex. eye color, home state, ethnicity)
Term
 Ordinal variables
Definition
 Categorical variables that HAVE a natural order. (ex. Fresh, Soph., Junior, Senior and Likert Scale- strongly agree, somewhat agree, etc.)
Term
 Interval variables
Definition
 Measurement variables for which differences are consistent but ratios are not. Ex. Temperature
Term
 Ratio variables
Definition
 Measurement variables for which ratios are consistent. Ex. age, height, distance, # of chairs in a room
Term
 Discrete variable
Definition
 measurement variable that you can actually count the # of possible responses. Ex. number of automobiles that wrecked on a freeway, 0,1,2,3 you cant have 2.8 or 3.6. YOU CAN COUNT THE AMOUNT WITHOUT HAVING TO ROUND THE NUMBER OFF
Term
 Continuous variable
Definition
 measurement variable that can be anything within a given interval. Ex. Age
Term
 Bias
Definition
 a systematic prejudice in one direction, survey questions may be worded in such a way that the responses are biased.
Term
 Variability
Definition
 discrepancies (vary from one to the next) between repeated measurements, Ex. measuring the length of a table with a ruler
Term
 Natural variability
Definition
 Variability that cannot be explained or predicted, Ex. unemployment.
Term
 Valid measurement
Definition
 measures what it claims to measure
Term
 Reliable measurement
Definition
 gives approximately the same result when repeated on the subject, Ex. bathroom scale
Term
 Confidential
Definition
 respondents identities are known but protected, these surveys allow a follow up
Term
 Anonymous
Definition
 respondents' identities are unknown, these surveys dont allow a follow up
Term
 Open question
Definition
Term
 closed question
Definition
 multiple choice
Term
 What do you want from a sample?
Definition
 -Representative and small as possible, but still reliable
Term
 Unit
Definition
 single individual or object
Term
 Frame
Definition
 a list of units from which the sample is chosen
Term
 Census
Definition
 a survey in which the entire population is measured
Term
 Simple Random SampleRequirements for selection?
Definition
 a sample collected in such a way that every conceivable group of units of the correct size has an equal chance of being the one selected. Requirements - a frame, a random # generator.
Term
 Sampling error
Definition
 random chance
Term
 Sampling error
Definition
 random chance
Term
 Nonsampling error
Definition
 poor methods
Term
 Margin of error is a measure of what?
Definition
 sampling error
Term
 Stratified Random SampleWhat are some advantages of this sampling?
Definition
 Procedure: divide the population into groups (strata) and then collect a simple random sample from each group.-The advantages have info on each strata available and its less expensive to conduct.
Term
 Cluster sample
Definition
 Procedure: divide the population into groups (clusters). Take a simple random sample of clusters and measure all units within the selected clusters."every subject from some groups"
Term
 Systematic sampling
Definition
 select units from the frame according to some pattern, perhaps every 10th person.Ex. select the first person in each row from a lecture hall.
Term
 Multi stage sampling
Definition
 a sampling plan that combines 2 or more sampling procedures.
Term
 Sampling disasters
Definition
 1) getting a volunteer sample, no pretense of randomization2)Using a convenience or haphazard sample - use whoever is standing around
Term
 Sampling disasters
Definition
 1) getting a volunteer sample, no pretense of randomization2)Using a convenience or haphazard sample - use whoever is standing around
Term
 Difficulties for sampling
Definition
 1)using the wrong frame, 2)not reaching the individuals selected, 3)non-response(volunteer response)
Term
 Response variable (RESP)
Definition
 the RESP is the primary measurement of interest. Usually a study considers only one RESP.
Term
 Explanatory variables (EXPL) or factors
Definition
 an EXPL is other info about each subject that may explain why the subjects differ in respect to the RESP, studies often have many EXPL
Term
 Typical situation
Definition
 compare 2 or more groups based on the RESP. The group is the EXPL.
Term
 Experiment
Definition
 a study which the EXPL is controlled (manipulated) by the researcher. EXPL is a treatment.
Term
 Observation studies
Definition
 a study in which the value of EXPL is determined by nature. The EXPL is an observation is not manipulated or controlled. EXPL is not treatment.
Term
 Confounding variable
Definition
 An extraneous difference in the groups.
Term
 Interacting variable
Definition
 A variable that changes the way the group compare with respect to the RESP.
Term
 Control group
Definition
 a treatment group that receives essentially no treatment
Term
 placebo
Definition
 a "fake drug" that looks like a real drug but has no active ingredients.
Term
 Placebo effect
Definition
 the tendency of subjects to respond to any treatment, even a "fake" one.
Term
 Hawthorne effect
Definition
 the tendency of subjects to react differently than they normally would because they are being observed
Term
 Experimenter Effect
Definition
 the tendency of researchers to "see" what they want (or expect) to see.
Term
 Retrospective studies
Definition
 subjects are asked to recall past events
Term
 Prospective studies
Definition
 subjects are followed into the future
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