Research Design

Question 1

Group designs vs single-subject designs

Answer 1

one or more groups of subjects exposed to one or more levels of the IV(‘s)
example: young vs old subjects, various levels of noise added to a speech recognition task

focus is on individual behavior, can include multiple subjects but they are not analyzed primarily as a group
example: looking at effects of various types of phonemic training, in a child (or children) with reading deficits

Question 2

Between subjects vs within-subjects designs vs mixed

Answer 2

all these can be group designs, group equivalence needs to make sure that factors such as age, education, gender, intelligence, etc don’t contribute to differences in the dependent variable
two strategies
- subject randomization
-subject matching

different groups of subjects are exposed to different levels of the IV
-sequencing effects
order effects
carryover effects
-two solutions
sequence randomization
counterbalancing

same subjects are exposed to different levels of the IV, require fewer subjects

use both between-subject and within-subject variables

Question 3

Test Validity

Answer 3

Face
Content
Predictive
Concurrent
Convergent
Discriminant

Question 4

Internal vs External Validity

Answer 4

experimental validity

the extent to which an experiment accurately measures what it intended to measure
-depends on how well the experiment was designed and controlled for relevant extraneous factors

the extent to which the results of an experiment can be generalized to a larger context, beyond the confines of the experiment itself
-also depends on good study design, to maximize generalizability

Question 5

Threats to Internal Validity/sources of excess variability

Answer 5

history
maturation
reactive pretest
instrumentation
statistical regression
differential subject selection
attrition
interaction of factors
credibility

Question 6

Generalizability