Research Designs Flashcards
When an elderly sample is selected from a local fitness center
“Healthy-user” bias
When the population is selected from an impaired or diseased group
Berkson’s Bias
When patients with certain characteristics are excluded
-Ex: racial groups, socioeconomic groups, etc
Exclusion Bias
Bias decreases
Generalizability
What are the two major classes of research designs?
- ) Experimental
2. ) Non-experimental/observational
Is characterized by random assignment, manipulation of independent variables, and control of extraneous factors
Experimental Research
Experimental research is the best form of research for
Cause-and-effect
Experimental research is the standard for
Clinical trials
Characterized by no control over group assignment and no control over independent variables
Non-experimental/observational research
Non-experimental/observational research can not be used to determine
Causality
What is the gold standard experimental design for treatment studies?
Randomized control trial (RCT)
Equivalent groups are needed to interpret effects. We randomize because randomization removes
Selection bias
In the physicians aspirin study, randomization was accomplished through
Computer generated random numbers
When the investigator “knows” the expected results and treats groups differently
Investigator bias
One way to control investigator bias is when the people randomizing individuals into groups are blinded as to which subjects go into which group. This is called
Allocation Concealment
Another way to prevent investigator bias is to blind the investigator who is providing treatments or making measurements as to which group is which. This is called
Investigator blinding
Investigator bias can me minimized by
Allocation concealment and investigator blinding
When subjects change their behavior in a study, for example, they may want to please the investigators so they act differently. This is called
Subject bias (Hawthorne effect)
The Hawthorne effect (subject bias) effects
External and internal validity
How is the Hawthorne effect combated?
Subject “blinding” by use of a placebo group
Using a placebo group does not really work if the study involves an obvious
Physical change
When patients and clinicians are both blinded
Double Blinding
Ambiguous term, generally used to mean that the subjects are blinded
Single-blinding
Besides just controlling the allocation and outcome of a study, a researcher also needs to control
Extraneous variables (i.e. diet, non-compliance, drop out, etc.)
