AP Statistics Chapter 4 Test Flashcards
population
the entire group of individuals we want info about
census
collects data from every individual in the pop.
sample
subset of individuals in the pop. from which we actually collect data
sample survey
study that collects data from a sample that is chosen to represent a specific pop.
convenience sample
choosing individuals from the pop. who are easy to reach; often produces unrepresentative data
voluntary response sampling; volunteers tend to have ____
allows people to choose to be in the sample by responding to a general invitation; strong opinions and are not representative of pop.
random sampling
chance process to determine which members of a pop. are included in a sample
simple random sampling
every individual in a chosen pop. has a chance of being selected
N
number of individuals in a pop
n
number of individuals in a sample size
strata
groups of individuals in a pop. who share characteristics thought to be associated with the variables being measured in a study
stratified random sampling
choosing an simple random sample from each stratum and combining the SRSs into one overall sample
cluster
group of individuals in pop that are located near the other
cluster sampling
randomly choose clusters and including each member of the selected clusters in the sample
systematic random sampling
ordered arrangement of pop; randomly selects one for the first k individuals and choose every kth individual thereafter
undercoverage
some members of the pop. are less likely or cannot be chosen in a sample
nonresponse
when an individual chosen for the sample can’t be contacted or refuses to participate
response bias
occurs when there is a systematic pattern of inaccurate answers to a survey question
observational study
observes individuals & measures variables of interest without influencing the responses
response variable
measures an outcome of a study
explanatory variable
helps explain or predict changes in response variable
confounding variable
two variables are associated in such a way that their effects on the response variable is indistinguishable
Experiment
deliberately impose some treatment on individuals to measure their responses
placebo
treatment with no active ingredient, but is otherwise like other treatments
Experimental unit
object to which a treatment is randomly assigned(e.g.: humans)
treatment
specific condition applied to the individuals in an experiment
factor
variable that is manipulated and may cause a change in the response variable
levels
different values of a factor
control group
used to provide a baseline for comparing the effects of other treatments; should be treated exactly the same as other treatment groups
placebo effect
some subjects in the experiment will respond favorably to any treatment, inactive or not
double-blind experiment
BOTH the subjects and experimenters don’t know which subjects are receiving the treatment
random assignment
Experimental units are assigned to treatments using a chance process
control
keeping other variables constant for all experimental units
replication
using enough experimental units to distinguish a difference in the effects of the treatments from chance variation due to the random assignment
completely randomized design
the experimental units are assigned to the treatments by chance
block
group of experimental units that are known before the experiment to be similar in some way that is expected to affect the response to the treatments
randomized block design
the random assignment of experimental units to treatments is carried out separately within each block
matched pairs design(1); two very…
two very similar designs are paired and the two treatments are randomly assigned within each pair
matched pairs design(2); each…
each experimental unit receives both treatments in random order
sampling variability
refers to the fact that different random samples of the sample size from the same population produce different estimates
the larger the sample size, _______ and _______.
less variability; higher precision
