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Statistics V

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random numbers
these are hard to generate, but several websites offer an unlimited supply of equally likely random values
Models a real-world situation by using random-digit outcomes to mimic the uncertainty of a response variance of interest.
Simulation Component
A component uses equally likely random digits to model simple random occurrences whose outcomes may not be equally likely.
any one of the possible results of an action
each result/observation of an experiment, such as one roll of a number cube.
Response variable
The variable being studied by the experimenter. The experiment will investigate how the response variable behaves when the investigator manipulates one or more explanatory variables or factors.
the entire group of items or individuals for which a sample is taken (the entire American _______________________, New jersey is a sample)
a randomly selected group chosen for the purpose of collecting data. ie 3 middle schools in Monmouth county to determine information regarding typical Middle School student in Monmouth County
sample survey
A study that asks questions of a sample drawn from some population in the hope of learning something about the entire population.
A systematic error that favors a particular segment of the population or that tends to encourage only certain outcomes in the data.
The best defense against bias; each individual is given a fair, random chance of selection.
any attempt to force a sample to resemble specified attributes of the population
Sample Size
Number of individuals in a sample represents the population.
Used to measure a variable for every unit of a population.
population parameter
Numericlaly valued attribute of a model for a population.
A sample is said to be _______________________ if the stats computed from it accurately reflect the corresponding population parameters.
Simple random sample
each possible sample is equally likely
sampling frame
The list of possible subjects who could be selected in a sample.
sampling variability
The natural tendency of randomly drawn samples to differ, one from another.
stratified random sample
A sampling design in which the population is divided into several subpopulations, or strata, and random samples are then drawn from each stratum.
cluster sample
A sampling design in which entire groups are chosen at random.
multistage sample
Sampling schemes that combine several sampling methods.
systematic sample
A sample drawn by selecting individuals systematically from a sampling frame.
voluntary response bias
Bias introduced to a sample when individuals can choose on their own whether to participate in the sample.
convenience sample
Consists of the individuals who are conveniently available to sample.
A sampling scheme that biases the sample in a way that gives a part of the population less representation.
nonresponse bias
Bias introduced when a large fraction of those sampled fails to respond.
response bias
Anything in a survey design that influences response.
observational study
The researcher observes the experimental units in their natural setting and records the variable(s) of interest. The researcher makes no attempt to control any aspect of the experimental units.
retrospective study
An observational study in which subjects are selected and then their previous conditions or behaviors are determined.
prospective study
An observational study in which subjects are followed to observe future outcomes.
an organized procedure for testing a hypothesis.
random assignment
to be valid, an experiment must assign experimental units to treatment groups at random
A number that divides evenly into another number. 3 is a factor of 15 (look at the chart!)
Dependent (response) variables
experimental units
Individuals on whom an experiment is performed.
The specific values that the experimenter chooses for a factor.
The process, intervention, or other controlled circumstance applied to randomly assigned experimental units.
principles of experimental design
control, randomize, replicate, block
statistically significant
when an observed difference is too large for us to believe that is is likely to have occurred naturally
Control group
Consists of the units who are not to receive the treatment that is the focus of the experiment
Any individual associated with an experiment who is not aware of how subjects have been allocated to treatment groups.
when either those who could influence or evaluate the results is blinded
when both those who could influence and evaluate the results are blinded
A treatment known to have no affect.
placebo effect
The tendency of many human subjects to show a response even when adminstered a placebo.
when groups of experimental units are similar, it is a good idea to gather them together into these
in a retrospective or prospective study, subjects who are similar in ways not under study may be ________ and then compared with each other on the variables of interest
randomized block design
randomization occurring within blocks
completely randomized design
all experimental units have an equal chance of receiving any treatment
when the levels of one factor are associated with the levels of another factor so their effects cannot be separated