Types of Studies
A study where the researcher observes & measures variables of interest, but does not attempt to influence the responses.
What is an Observational Study?
Uses readily available subjects.
What is Convenience Sampling?
When a sample is comprised entirely of volunteers or people who choose to participate.
What is Voluntary Response Bias?
Group is treated identically in all respects to the group receiving the treatment, except that this group doesn't receive the treatment.
What is a Control Group?
A polling company wants to know what all U.S. voters think. They randomly survey 1,200 registered voters. What is the population?
What are US Voters?
A part of the information we examine to gather information about the population.
What is a Sample?
The sample is obtained by allowing subjects to decide whether or not to respond.
What is a Voluntary Response Sample?
Occurs when some groups in the population are left out of the process of choosing a sample.
What is Undercoverage Bias?
A dummy treatment.
What is a Placebo?
A school tests a new learning method by using it with half the classes and comparing scores. What kind of study is this?
What is an Experiment?
The entire group we want information from.
What is a Population?
Consists of "n" individuals from the population chosen in such a way that every set of "n" individuals has an equal chance in the sample selected.
What is Simple Random Sample (SRS)?
Occurs when an individual chosen for a sample can't be contacted or refuses to respond.
What is Non-Response Bias?
When the subject does not know what treatment they are receiving, to remove the power of suggestion.
What is Blinding?
A restaurant manager surveys only the customers sitting in the front booths. What sampling bias might be present?
What is Convenience Bias or Undercoverage Bias?
Collect data from every individual in a population.
What is a Census?
Divides the population into groups of similar individuals, then selects an SRS within each group.
What is Stratified Random Sampling?
People give silly answers just so that they won't appear like they know nothing about the subject.
What is Response Bias via Ignorance?
Experiments in which the subject & administrator do not know who receives the treatment.
What is a Double Blind?
A hospital runs a trial where neither doctors nor patients know who gets the real drug. What is this method called?
What is a Double Blind Experiment?
Deliberately imposes some treatment on individuals to measure their responses.
What is an Experiment?
Randomly selects an arbitrary starting point, then selects every "kth" member of the population.
What is Systematic Random Sampling?
People give the wrong answer simply because they don't remember the correct one.
What is Response Bias via Lack of Memory?
Variables that might affect the outcome, but are never controlled or accounted for in an experiment.
What are Confounding Variables?
A company splits employees into departments and samples 5 people from each. What sampling method is this?
What is Stratified Random Sampling