Ap statistics
Simple Random sample
(SRS) of size n consists of n individuals from the population chosen in such a way that every set of n individuals has an equal chance to be the sample actually selected.
Population
A census is a complete sample of the entire...
Treatment
A specific condition applied to the individuals in an experiment is called a treatment. If an experiment has several explanatory variables, a treatment is a combination of specific values of these variables.
Stratified sample
An example of this method is to randomly draw from a group of males and a group of females.
Statistically significant
An observed effect so large that it would rarely occur by chance
Placebo effect
An untreated subject incorrectly believes he of she recieved a treatment.
Systematic sample
Choose a sample such that every kth element from a population is chosen.
Convenience sample
Choosing individuals who are easiest to reach results in a
Cluster
Divide population into sub group mimic the same characteristics of population.
Random assign
Implies effect and cause
Double blind
In a experiment, neither the subjects nor those who interact with them and measure the response variable know which treatment a subject received.
Random assignment
In an experiment, means that experimental units are assigned to treatments at random, that ism using some sort of chance process.
Experiment
In this type of study, we apply a treatment and then observe the effects.
Random sampling
Infer results can be extended from the sample to population.
stratification(stratifi)
Observational study, back up.
Stratified sample
Subdivide the population into at least two difference subgroups and draw a sample from each.
BIas
The design of statistical study if it systematically favors certain outcomes.
Rare event
The probability that an event will happen is less than 0.5%
Inference
The purpose of a sample is to give us information about a larger population. The process of drawing conclusions about a population on the basis of sample.
Alternative hypothesis
The research hypothesis
Retrospective study
Treated subjects respond differently is an example of
Variation
Treated subjects respond differently is an example of--
Double blind study
When neither the doctor nor the patient knows who is getting the drug and who is getting the placebo.
Experiment units
are the smallest collection of individuals to which treatments are applied. When the units are human beings, they often are called subjects.
Simple random sample
choose a sample such that every possible sample of size n has an dqual chance of being chosen.
Experiment
deliberately imposes some treatment on individuals to measure their responses.
Random assignment
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Cluster Sample
divide the population into subgroups and randomly select some entire subgroups as the sample.
Stratified random sample
first classify the population into groups of similar individuals, called strata. Then choose a separate SRS in each stratum and combine these SRSs to form the full sample.
Cluster sample
first divide the population into smaller groups. Ideally, these clusters should mirror the characteristics of the population. Then choose an SRS of the clusters. All individuals in the chosen clusters are included in the sample.
Random sampling
from population
population
in a statistical study is the entire group of individuals about which we want information.
Block
is a 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 treatment.
Lurking variables
is a variable that is not among the explanatory or response variables in a study but that may influence the response variable.
Sample
is the part of the population from which we actually collect information. We use information from a sample to draw conclusions about the entire population.
Voluntary response sample
it consists of people who choose themselves by responding to a general appeal. Voluntary response samples show bias because people with strong opinions (often in the same direction) are most likely to respond.
Observational study
it observes individuals and measures varialbes of interest but does not attempt to influence the responses.
Nonresponse
it occurs when an individual chosen for the sample can't be contacted or refuses to participate.
Undercoverage
it occurs when some groups in the population are left out of the process of choosing the sample.
Confounding
it occurs when two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other.
Population
the group you are trying to make inferences about
Experiment
the only way to establish cause and effect
randomized block design
the random assignment of experimental units to treatment is carried out separately within each block.
Placebo effect
the response to a dummy treatment is called.
Completely randomized design
the treatments are assigned to all the experimental units completely by chance.
Block
with experiment-> treatments and controlled group.
