Ch. 5: Experiments and Observational Studies
Disasters in Experiments
-Confounding variables -Interacting variables -Placebo, Hawthorne, and Experimenter effects -Ecological validity
Disasters in Observational Studies
-Confounding variables and the implications of causation -Extending the results inappropriately -Using the past as a source of data
Reasons for Observational Study
-Unethical or impossible to assign people to a particular treatment ex. drug use, disease, education -Some traits are inherent and cannot be randomized ex. sex, age, race
Advantages of Case Control Observational Studies
-efficiency -reducing potential confounding variables
Case Control Observational Study
A group that does not have the particular characteristic or attribute as the group of interest being studied
Control Group
A group that does not receive the treatment
Which of the following defines what is meant by a control group in an experiment? -a group that is used by researchers to monitor how the experiment is going -a group that is handled identically to the treatment group(s) in all respects except that they don't receive the active treatment -a group that is handled identically to the treatment group(s) in all respects except that they are controlled to a greater extent than the other groups, providing baseline data -none of the above
A group that is handled identically to the treatment group(s) in all respects except that they don't receive the active treatment
Which of the following influences on the experimental units can bias the results of an experiment? -placebo effect -Hawthorne effect -not being blinded -all of the above
All of the above
Which of the following is a potential complication of observational studies? -confounding variables -improper extension of the results -the improper conclusion of causation -all of the above
All of the above
Randomized Experiment
Create differences in the explanatory variable and examine the results in the response variable
What does randomization mean in terms of experiments? -The researchers randomly select which treatments they will include in the experiment. -Each of the experimental units is randomly selected to participate. -Each of the experimental units is randomly assigned to a treatment. -none of the above
Each of the experimental units is randomly assigned to a treatment
Blinding
Either the researcher and/or participants do not know which treatment they are receiving, intended to eliminate bias
Which of the following is not a type of observational study? -introspective study -case-control study -prospective study -retrospective study
Introspective study
Placebo
Looks like the real medication but has no active ingredients
Repeated Measures
Multiple measures on the same participants ex. before and after
Double Blind
Neither the researcher nor the participants know which treatment the participant is receiving
Matched Pairs
Not the exact same participants but each participant in one group is paired with one participant in the other group ex. twins, couples, medical (sex, weight, height)
Confounding variables are a bigger problem in an (blank) study
Observational
(Blank) can only measure and analyze if confounding variables are related to response variable
Observational studies
Observational Studies
Observe differences in the explanatory variable and notice whether these are related to differences in the response variable
Confounding Variables
Occurs when it is difficult to tell if the difference in the outcomes is due to a treatment (or specific variable) or due to some other unknown variable (confounder) -related to the explanatory variable -affects the response variable
Interaction
Occurs when the relationship of one of them to the response variable depends on the other one
Retrospective Observational Study
Participants are asked to recall past events, reviewing old records
Prospective Observational Study
Participants are followed into the future and events recorded
Hawthorne Effect
People behave differently just because they are part of an experiment
Placebo Effect
People get better because they think they are on medication
Experiments use (blank) to reduce the effects of confounding variables and other sources of bias that are naturally present in observational studies.
Randomization
(Blank) can control for some confounding variables
Randomized experiment
An observational study that asks participants to recall their first childhood memory is a (blank) study
Retrospective
Effect Modifier
Subgroup variable that modifies the effect of the explanatory variable on the outcome
Ecological Validity
The methods, materials, and the setting of the study must approximate the real world that is being examined
Single Blind
The researcher know which treatment the participant is receiving but the participant does not know
Experimenter Effect
The researcher's bias impacts the study
Block Design
Treatment randomly assigned within each block (group)
Interacting Variables
Two explanatory variables (X) the result in different relationships with the response variable
Random assignment deals with what aspect of an experiment? -who the results can be applied to -whether or not a cause and effect relationship exists -what the actual statistical results are -none of the above
Whether or not a cause and effect relationship exists
Random sampling deals with what aspect of a study? -whether or not a cause and effect relationships exists -who the results can be applied to -what research question is being asked -what the actual statistical results are
Who the results can be applied to