Sampling
People who volunteer to be in a sample. This is biased. It is called a....
Voluntary Response Sample
Individuals selected for a sample cannot be reached.
Nonresponse bias
when subjects respond favorably to a placebo as it were the actual treatment
placebo effect
Observational studies are performed in this setting
natural
The subject does not know whether they have the treatment or the placebo.
Single-blind experiment
Choosing individuals who are easy to reach.
Convenience Sampling
A group of the population is left out of the process when choosing a sample.
Undercoverage
A dummy treatment used to see if something works. Looks the same as the real treatment.
Placebo
Observational studies look for....
correlation between an explanatory variable and a response variable
Neither the subject nor the experimenter knows who has the treatment and who has the placebo.
Double-blind experiment
Divide population into homogenous groups, perform a simple random sample in each group.
Stratified Random Sample
The respondent or interviewer cause the questions to be dishonest.
Response bias
Humans are known as
subjects
An example of an ethically challenging observational study would be...
smoking and lung cancer
What is being measured and used for comparison.
Response variable
Gives each person in a population the same chance of being chosen.
Simple random sample
Wording of the questions or choices cause the respondent to be mislead.
Leading question
The 3 principles of experimental design
Control, randomization, duplication
lurking variables
Specific values of a treatment
Level
Randomly choose the first person, then choose more people from the population at a regular interval.
Systematic Random Sample
Causation about an experiment when unequal/unfair conditions introduce bias that cannot be easily identified.
Hidden Bias
In experiments we must watch out for...
confounding variables
observational studies do not involve...
treatments
What does this equation represent???!!!!!! Read carefully.
( Σ (x-μ)² ) / N
Population Variance