Chapter 9 Flashcards
What are within-subject designs?
A research design in which the different groups of scores are all obtained from the same group of participants.
What are the advantages to within-subject designs?
- The inclusion of multiple measures from each participants reduces the impact of individual differences
- More power (requires a smaller number of participants than other designs)
- Less expensive – less labor intensive
What are the inconveniences of within-subjects designs?
Impossible to use for certain research questions
- participants have to be blind to the hypotheses
- levels of the independent variable include participants from mutually exclusive groups (e.g., men and women, reading disability vs. control…)
Designs more complex
Which design is more powerful?
Within-subject designs are much more powerful than between because with fewer participants, you can show that a design IS statistically significant. You can compare participants to themselves because you take at least two measurements of the same person.
What is history? What is this a threat to?
Any outside event(s) that that influence the participants’ scores in one treatment differently than in another treatment.
Threat to internal validity because any differences that are observed between treatment conditions may be caused by history instead of the treatments
What is Maturation? What is it a threat to?
Any physiological or psychological change that occurs in participants during the study and influences the participants’ scores.
Threat to internal validity because observed differences between treatment conditions may be caused by maturation instead of the treatments.
What is instrumentation? What is this a threat to?
refers to changes in the measuring instrument that occur during a research study in which participants are measured in a series of treatment conditions.
Threat to internal validity because any observed differences between treatment conditions may be caused by changes in the measuring instrument instead of the treatments.
What is regression towards the mean a threat to?
Threat to Internal validity because changes that occur in participants’ scores from one treatment to the next can be caused by regression instead of the treatments.
What are Order Effects?
when the experience of being tested in one treatment condition has an influence on the participants’ scores in a later treatment condition.
What are Carry-over effects?
Occur when one TREATMENT CONDITION produces a change in the participants that affects their scores in subsequent treatment conditions.
What is Progressive Error?
changes in a participant’s behaviour or performance that are related to general experience in a research study but NOT related to a specific treatment. Ex: practice effects and fatigue
What is Counterbalancing?
In a within-subjects design, a procedure to minimize threats from order effects and time-related factors by changing the order in which treatment conditions are administered from one participant to another so that the treatment conditions are matched with respect to time.
The goal is to use every possible order of treatments with an equal number of individuals participating in each sequence.
What is Partial Counterbalancing? What is used to do this?
A system of counterbalancing that ensures that each treatment condition occurs first for one group of participants, second for one group, third for one group, and so on, but does not require that every possible order of treatment conditions be used.
Latin square. An N×N matrix where each of N different items appears exactly once in each column and exactly once in each row. Used to identify sequences of treatment conditions for partial counterbalancing.
What is a matched-subjects design?
Each individual in one group is matched with a participant in each of the other groups. The matching is done so that the matched individuals are equivalent with respect to a variable that the researcher considers to be relevant to the study.
