exam 3 Flashcards
Which variable is manipulated?
Independent variable
Which variable is measured?
Dependent variable
Any variable that an experimenter holds constant
Control variable
T/F Everything should be held constant except what is being manipulated.
True
Why Experiments Support Causal Claims?
They Establish:
1. covariance
2. temporal precedence
3. internal validity
What group has no treatment condition?
Control group
What group has one or more treatment condition?
Treatment group
placebo control group is called
Placebo group
The group with the comparison condition is
Comparison group
What is a design confound?
accidental second variable is an alternative explanation for the results. Systemic variability is the problem.
Which variability has levels of variables that coincide in some ways causing confounds?
Systematic Variability
Unsystematic Variability
Levels of variables fluctuate independently leading to variability
When participants at one level are systematically different than those from the other level which effect is this and what does it affect?
Selection effect; Internal Validity
Random Assignment
random method to assign participants
Define matched groups
participants who are similar are grouped together
Independent groups design
different groups are exposed to different levels of the independent variable
Within-groups design
each participant is exposed to all levels of the IV
participants are tested on the dependent variable only once.
Posttest-only design
participants are tested on the dependent variable twice (once before and once after exposure to independent variable)
Pretest/Posttest Design
Taking an exam as a group, and then taking the test individually would be problematic to which design?
pretest-postest design
How is construct validity established in dependent variables?
By how well the variables are measured
How is construct validity established in independent variables?
By how well the variables are manipulated
How can you test how well an independent variable was manipulated?
1.Manipulation Checks
2. Pilot studies
an extra dependent variable that researchers can include to determine how well a manipulation worked
Manipulation checks
What is a pilot study?
a study before (or sometimes after) to test effectiveness of manipulations..
participants are measured on a dependent variable more than once, after exposure to each level of the independent variable.
Repeated Measures Design
participants are exposed to all the levels of an independent variable at the same time
Concurrent- measures design
Name 2 advantages of within-groups design
- Participants in your groups are equivalent
- requires fewer participants than other designs
How does counterbalancing avoid order effects?
they present the levels of the independent variable to participants in different sequences
threat to internal validity where people change overtime just by random happenings
Maturation threat
Ex: 1st grade teacher measures words at the beginning of the school year in students vs words they know at the end of the school year. The increase in words could be from the curriculum or could simply just be from their brains growing. What type of threat is this?
Maturation threat
How can maturation threats be solved?
By adding a control group
An experimental group changes over time because of an external factor that affects all or most members of the group
History threat