[L5] Repeated Measures Experiments

Question 1

Two Types of Experimental Designs

Answer 1

Repeated Measures Design
Independent Groups Design

Question 2

comparing the scores of
individuals in one condition against their scores in
another condition.

Answer 2

Repeated Measures Design

Question 3

comparing the scores of
one group of people taking one condition against the
scores of a different group of people in the other
condition.

Answer 3

Independent Groups Design –

Question 4

Other Names:

Answer 4

Within-subjects studies / designs
Related groups / design
Cross-over studies / design

Question 5

change within a
group of individuals, rather than between two groups.

Answer 5

Within-subjects studies / designs –

Question 6

people undergoing two
different treatments are closely matched, so that the two
groups are not independent, rather they are related.

Answer 6

Related groups / design –

Question 7

*strictly speaking, a ___design is a type
of related design; however, it is very rare to encounter a
study where both groups are ____.

Answer 7

repeated measures; sufficiently closely
matched

Question 8

term mainly used in
medical research than commonly used in psychology.
People cross-over from one group to the other group.

Answer 8

Cross-over studies / design

Question 9

Common Mistakes:

Answer 9

Correlational and Repeated Measures
Designs

Question 10

__ – when we want to see if people who
were high scorers on one test are also high scorers on the
second test. We are not interested in whether the scores
overall have gone up or down.

Answer 10

Correlational

Question 11

– if people on average, score
higher on one occasion than the other.

Answer 11

Repeated Measures

Question 12

Advantages of Repeated Measures Design

Answer 12

1. There is no need for many participants.
2. Each person acts as their own (perfectly) matched
   control group.

Question 13

Disadvantages of Repeated Measures Design

Answer 13

1. Practice effects
2. Sensitization –
3. Carry-over effects

Question 14

participants gets better at a task over
time. (solutions: counterbalancing and practice items)

Answer 14

Practice effects –

Question 15

– participants may perceive that a
dependency exists between two measures, and
deliberately keep their answers similar when we are
looking for change. Alternatively, because the
participants perceive that the researcher is looking for
change, they might change their answers.

Answer 15

Sensitization

Question 16

occurs when something about the
previous condition is “carried over” into the next
condition.

Answer 16

Carry-over effects –

Question 17

Statistical Tests for Repeated Measures Designs

Answer 17

1. The Repeated Measures t-test –
2. The Wilcoxon test
3. The Sign Test

Question 18

parametric test for
continuous data.

Answer 18

The Repeated Measures t-test –

Question 19

non-parametric test for ordinal
data

Answer 19

The Wilcoxon test –

Question 20

non-parametric test for categorical
data

Answer 20

The Sign Test –

Question 21

the most powerful, and most likely to spot
significant differences in data. It can not be used
however with all repeated measures data. Data should
also satisfy some conditions before this test can be used.

Answer 21

t-test -

Question 22

deals with all data that can be ordered
(ordinal data).

Answer 22

Wilcoxon test –

Question 23

– only deals with data in the form of categories
(nominal data). Easy to understand and calculate.

Answer 23

Sign test

Question 24

Down side of _____ – only deals with crude categories, rather
than rich data of ranks or intervals.

Answer 24

Sign test

Question 25

The Repeated Measures t-test
To use this test, we need to make 2 assumptions about our
Data:

Answer 25

The data are measured on a continuous (interval)
level.
2. The differences between the two scores are normally
distributed.

Question 26

It makes no assumption about the distribution of the
scores. Only the ___ between the scores.

Answer 26

differences

Question 27

It is possible to have variables which have highly ___, but which have normally
distributed differences.

Answer 27

nonnormal
distributions

Question 28

It makes no assumption about the ___ of the
variables.

Answer 28

variances

Question 29

Given a sufficiently large sample, the repeated measures
t-test is ____ of both these
assumptions.

Answer 29

robust against violations

Question 30

Above sample sizes of approximately ___, the test
becomes very robust to violations of distributional
assumptions.

Answer 30

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