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what is observational study?
observe individuals and measure variables of interest but do not attempt to influence the response.

what is experiement?
impose treatment on individual.

what's population?
group trying to study

what's sample?
the group within the population

what's a census?
ask everyone in the population

what's sampling?
cutting/ dividing groups and putting data together.

what do you use if the population is huge?
use sampling

what do you use if the population is small?
census

which is often more accurate? sample or census?
a carefully conducted sample is often more acurate than a census.

what's a voluntary response sample? g/b?
bad. examples include callinpolls, online polls. it has negative opinions and you cannot trust the results.

what's convenience sampling? g/b?
ex: choosing individuals who are easy to reach.

what's simple random sampling?
 randomly choose people.
 it gives everyone a chance and it avoids favoritism and being biased.
ex. pulling names out of a hat or assigning numbers.

what's stratisfied random sampling?
when a whole population is cut up into stratas and you gather the data from SRS.

what's cluster sampling?
you dividie the population and randomly select clusters. all the individuals in that chosen cluster will be in the sample.

what is sample error?
refers to the natural variability between samples

when does response bias happen?
example?
 when the question leads to misleading results.
 people don't want to be perceived as having un popular, unsavory or illegal views.

what's undercoverage bias?
when part of the population is ignored.

what's systematic sampling?
when choosing a random point to start and then picking every nth person.

what two groups does experiment have?
treatment group and a control group

what's blocking?
example?
divides the subjects into representative groups. example: blocking by gender, age or race.

what are lurking variables?
thingsthat are not taken into account.

which 3 experimental designs can you choose from?
randomized design, blocking design and matched pair design.

what's a welldesigned experiment checklist?
randomization, control group, replication.

what's an experimental unit/subject?
 unit > not human
 subjects > human

what is a factor?
it's the explanatory variable

