Studied by 18 people
observational study
observe individuals and collect data without any interference with conditions
what are the two different types of observational studies
retrospective and prospective
Retrospective observational study
an observational study that has already occured
prospective observational study
an observational study being studied as it ocurs
experiment
deliberately impose some treatment on individuals to observe their responses
confounding variable
things that get in the way
simulation
mimic a situation and is alternative method for producing data when it may not be possible to carry out the experiment
population
the entire group from which you want to collect data
sample
part of the population that is actually examined
sampling
involves studying a part in order to obtain information about the whole group
census
when every member of the population is accounted for
response variable
measure the outcome of the study
explanatory variable
acounts for predicts and explains changes in the response variable
simple random sample
every possible set of n size individuals has an equal chance of being selected
stratified random sample
1st divide population into groups then perform SRS on each strata
another word for groups
strata
systematic sample
1st person is selected then each nth member after that
multi-stage
divide the population into groups, randomly select a group and survey all members of that group
convenience
sample based on avaliability
Errors that lead to bias:
confounding variables, under-coverage, non response, voluntary response, and response bias
undercoverage
when an entire group is excluded and not represented and did not have the opportunity to be included
non response
when someone is chosen to participate and chooses not to
voluntary response
people who chose to participate
response bias
respondents lie within answers
What do greek letters usually stand for?
an entire population
What do symbols typically stand for?
a specific sample
sampling frame
the list of individuals from which a sample is actually selected
What are the three principles of experimental design and explain each of them.
control: by comparing different treatment you can control outside influences
randomization: makes more impersonal which decreases bias
replication: repetition of experiments decreases variation
blocking
relates to a design of an experiment (randomize within each block) reduces variation!
experimental units
what or who you are performing the experimentation people are usually known as subjects
factors
are explanatory variable
level
when different values of an explanatory variable are used
treatment
condition being applied to the experimental unit (#factors)(#levels)=#of treatments
Note 
Flashcard (55)