Chapter 4 Flashcards
Experiment
Assigning subjects to certain
experimental conditions and then observing outcomes on
the response variable (or variables).
Observational study
Merely observes rather
than experiments with the study subjects.
Census
Count the number of people in the population and measure certain characteristics.
Sampling frame
The list of subjects in the population
from which sample is taken.
Sampling design
Method for selecting subjects from sampling frame.
Simple random sampling
Subjects from a population where each have equal chance of being selected
Bias
When results from the sample are not representative of
the population
Undercoverage
Having a sampling frame that lacks representation from parts of the population.
Sampling bias
Using nonrandom samples or having undercoverage.
Nonresponse bias
Some sampled subjects
cannot be reached or refuse to participate or fail to answer some questions.
Response Bias
When subject lies or question is asked in a misleading way
Convenience sampling
Type of survey sample that is easy to obtain relatively cheaply.
Volunteer sampling
Volunteers do not tend to be representative of the
entire population.
Treatment
A specific experimental condition imposed
on the subjects of the study
Experimental Unit
The subjects of an experiment; the
entities being measured
Control group
Not given treatment; basis of comparison
Placebo
A fake treatment; most subjects still respond to this
Blind Study
Subjects do not know what treatment(s) they recieve
Double-blind study
Both subjects and researchers do not know what treatment is given to which participant.
Cluster Sample
Population divided into large clusters; select random sample of clusters; use those subjects
Stratified Random Sample
Divide the population into separate groups, called
strata, based on some attribute; Select a random sample from each stratum.
Retrospective Study
Backward looking into the past
Case control study
A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls).
Factor of an Experiment
Categorical explanatory variables in an experiment
Matched-Pairs Design ExperimentA matched-pairs design in which subjects cross over during
the experiment from using one treatment to using another treatment
