Part 1
What is systematic variability?
in an experiment, the levels of a variable coinciding in some predictable way with experimental group membership, creating a potential confound
What is a within-groups design?
there is only one group of participants and each person is presented with all levels of the independent variable
What is a concurrent-measures design?
participants are exposed to all the levels of an independent variable at roughly the same time, and a single attitudinal or behavioral preference is the dependent variable
What is counterbalancing?
present the levels of the independent variable to participants in different orders
What is a pilot study?
a small study carried out to test the feasibility of a larger one
What is unsystematic variability?
in an experiment, when levels of a variable fluctuate independently of experimental group membership, contributing to variability within groups
What is a within-groups design?
there is only one group of participants and each person is presented with all levels of the independent variable
What is power?
Refers to the probability that a study will show a statistically significant result when an independent variable truly has an effect in the population.
What is full counterbalancing?
all possible condition orders are represented
What is a one-group, pre-test/ post-test design?
A researcher recruits one group of participants, measures them on a pre-test, exposes them to a treatment, intervention, or change, and then measures them on a post-test.
What are selection effects?
the likelihood that a non-representative sample may lead to inaccurate results
What is a post-test only design?
participants are randomly assigned to independent variable groups and are tested on the dependent variable once
What are order effects?
Threat to internal validity, being exposed to one condition changes how participants react to the other condition
What is partial counterbalancing?
Some, but not all, of the possible condition orders are represented
What is a maturation threat?
A change in behavior that emerges more or less spontaneously over time.
What are matched groups?
an experimental design technique in which participants who are similar on some measured variable are grouped into sets; the members of each matched set are then randomly assigned to different experimental conditions
What is a pre-test/ post-test design?
participants are randomly assigned to at least two groups and are tested on the key dependent variable twice- once before and once after exposure to the independent variable
What are practice effects?
Aka fatigue effects, a long sequence might lead participants to get better at the task, or to get tired or bored toward the end
What is a latin square?
A formal system of partial counterbalancing that ensures that each condition in a within-groups design appears in each position at least once.
What is a history threat?
Result from a "historical" or external factor that systematically affects most members of the treatment group at the same time as the treatment itself, making it unclear whether the change is caused by the treatment received.
What is an independent-groups design?
Different groups of participants are placed into different levels of the independent variable.
What is a repeated-measures design?
A type of within-groups design in which participants are measured on a dependent variable more than once - that is, after exposure to each level of the independent variable.
What are carryover effects?
some form of contamination carries over from one condition to the next
What is a demand characteristic?
Create an alternative explanation for a study's results
What is a regression threat?
refers to a statistical concept called regression toward the mean. When a group average (mean) is unusually extreme at time 1, the next time that group measured (time 2), it is likely to be less extreme- closer to its typical average performance.