Bias
Any systematic failure of sampling method to represent its population is called this.
What is bias?
A sample which consists of the individuals who are conveniently available.
What is convenience sampling?
the number of individuals in a sample
What is sample size?
This manipulates factor levels to create treatments, randomly assigns subjects to these treatment levels, and then compares the responses of the subject groups across treatment levels.
What is an experiment?
A study based on data in which no manipulation of factors has been employed.
Bias introduced to a sample when individuals can choose on their own whether to participate in the sample.
What is voluntary response bias?
A sample drawn by selecting individuals systematically from sampling frame.
What is systematic sampling?
the experimental units assigned to a baseline treatment level, or a placebo treatment.
To be valid, an experiment must assign experimental units to treatment groups at random.
What is random assignment?
A observational study in which subjects are selected and then their previous conditions or behaviors are determined.
What is a retrospective study?
Bias introduced when a large fraction of those sampled fails to respond.
What is nonresponse bias?
A sampling design in which entire groups are chosen at random.
What is cluster sampling?
When there are pre-existing differences among groups of experimental units, it is often a good idea to gather them together into blocks.
Individuals on whom an experiment is performed, usually called subjects or participants.
What are experimental units?
An observational study in which subjects are followed to observe future outcomes.
Anything in the survey design that influences responses falls under the heading of this type of bias.
What is response bias?
A sampling design in which the population is divided into several subpopulations (strata) and random samples are then drawn from each stratum.
What is stratified random sampling?
A treatment known to have no effect, administered so that all groups experience the same conditions.
The specific values that the experimenter chooses for a factor are called __________ of the factor.
What is a level?
When an observed difference is too large for us to believe that it is unlikely to have occurred by chance.
What is statistically significant?
A sampling scheme that biases the sample in a way that gives a part of the population less representation than it has in the population.
What is undercoverage?
Sampling schemes that combine several sampling methods.
What is blinding?
What is response?
It's just not possible for observational studies, whether prospective or retrospective, to demonstrate _____________________________.