Flashcards in quiz 2 Deck (65)
Explain a randomized control trial
When you take a group of volunteers, and randomly assign them to two groups.
One groups gets an intervention and the other gets a non-intervention or placebo. These two groups are compared to see if there's a difference between them overtime.
What is a confounding variable?
An alternative explanation for a relationship that has been observed
Why are RCTs good at dealing with confounding variables?
In an RCT, the confounding variable will equally affect both of the randomly split group in the RCT
What is a population?
persons, objects, or events that meet a specific set of criterias
What is a target population?
the larger population to which results of a study will be generalized to
What is an accessible population
the actual population of subjects available to be chosen for a study. (a subset of the target population)
What is a sample?
a subgroup of the accessible population which allows the results to be generalized to the population
What is a sampling bias?
the extent that sample SYSTEMATICALLY misrepresents populations. Can be conscious or unconscious
What is a sampling error?
the extent that a sample RANDOMLY misrepresents population
What are the types of sample techniques?
Probability samples and non-probability samples
What is a probability sample?
Random selection (or other known probability). Sample is considered, representative of population(although it may not be).
Can estimate sampling error
What is a non-probability sample?
Non-random samples. Generalization is difficult.
Can't estimate sampling error (should not use inferential statistics)
Types of probability sampling
Simple random sampling, systematic sampling, stratified random sampling, and cluster sampling
What is simple random sampling?
Random sampling. Everyone has an equal chance of getting in the study
What is systematic sampling?
systematically choosing samples. Ex: selecting every 10th person from a group. So you can estimate the probability of a person being in the sample
What is stratified random sampling?
specifying a number from each category in the sample.
Ex: 20 students from each grade level
What is a cluster sampling?
Types of non-probability sampling
convenience sampling, quota sampling, purposive sampling
What is convenience sampling?
when subjects are chosen on basis of availability. This is the most common form
Types of convenience sampling
- Consecutive sampling: recruit everyone to meet inclusion/exclusion criteria
- Volunteers(flyers/ads): what attributes lead subjects to volunteer & potential bias of self-selection
What is quota sampling?
Like stratified, where you select a specific amount from each category, but this is not random
What is purposive sampling?
where subjects are hand-picked by specific criteria. Ex: case series
What is an extraneous variable?
any factor not related to the purpose of the study, which may affect dependent variables.
- can become confounding variable if uncontrolled
3 essential components of experimental research
- include a control or comparison group.
- independent variable manipulated by the experimenter
- subjects are randomly assigned to groups, as opposed to naturally occurring or provider choice
What is random assignment?
each subject has an equal chance of being assigned to any group.
- helps control for extraneous variables or prognostic indicators
Random sampling is used to ____.
Random assignment is used to _____.
Generalize to a population.
Equalize two groups (controls and experimental)
What is concealing allocation?
Separating people should do the "random assignment" & data collection.
Sealed envelopes and locked cabinets
What is blinding?
To control conscious & unconscious bias in anyone involved in a study.
What is a single blind?
A case where just the measurer is blinded