Week 8 Flashcards

1
Q

Define a repeated-measures design and what is it sometimes called?

A

Sometimes called “within-subject design”, the dependent variable is measured two or more times for each individual in a single sample.

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2
Q

Explain how a repeated-measures design differs from an independent-measures design.

A

Single sample as opposed to two or more samples.

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3
Q

Define a matched-subjects design.

A

Each individual in one sample is matched on a particular variable with an individual in the other sample.

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4
Q

Explain how a matched-subjects design differs from a repeated-measures design.

A

Repeated measures designs have perfect matching, matched-subject have partial matching.

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5
Q

Explain how a matched-subjects design differs from an independent-measures design.

A

Each sample is matched on variables rather than being two or more randomly selected groups.

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6
Q

Describe the data that are used for the repeated-measures t statistic.

A

Uses D scores rather than X scores.

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7
Q

Describe the hypotheses for a repeated-measures t test.

A

H₀: μD = 0 and H₁: μD ≠ 0.

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8
Q

What are D scores?

A

The difference between X₁ and X₂ (before and after treatment).

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9
Q

What is MD? (D is subscript)

A

Mean of D scores.

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10
Q

What is μD?

A

The mean of difference scores for the whole population.

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11
Q

What is the t-statistic formula for a repeated measures design?

A

t = MD - μD/sMD

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12
Q

What is sMD? (M and D are subscript)

A

The estimated standard error of MD.

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13
Q

The related-samples t statistic requires two basic assumptions, what are they?

A
  1. The observations for treatment condition must be independent.
  2. The population distribution of difference scores (D values) must be normal (or large).
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14
Q

What is the estimated Cohen’s d for repeated measures designs?

A

d = MD/sD

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15
Q

How does the r² test (better known as ω²) differ for independent measures t tests and repeated measures t tests?

A

It doesn’t, it is always r² = t²/t² + df.

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16
Q

What is the confidence interval formula for repeated measures t tests?

A

μD = MD ± tsMD

17
Q

Larger samples produce a larger value for the t statistic (farther from zero) and increases the likelihood of rejecting H₀, TRUE OR FALSE?

18
Q

Larger variance produces a smaller value for the t statistic (closer to zero) and reduces the likelihood of rejecting H₀, TRUE OR FALSE?

19
Q

How does variance in D scores indicate consistency of treatment?

A

Little variance in D scores indicates that the treatments have approximately the same effect on all subjects.

20
Q

What are the advantages of repeated measures designs?

A
  1. Requires fewer subjects.
  2. Allows observation of change over time.
  3. Removes individual differences.
  4. Significantly less variance.
21
Q

What are the disadvantages of repeated measures designs?

A
  1. Order/sequencing effects.

2. Time factors.

22
Q

What is a nuisance variable?

A

A type of extraneous variable that increases the variability within participants in an experiment.

23
Q

What are the two main types of nuisance variables?

A
  1. Participant.

2. Environment.

24
Q

How do you control participant nuisance variables?

A
  1. Repeated measures designs with counter balancing.
  2. Matched-designs (variables can be overlooked and missed however).
  3. Independent group design (requires larger groups).
25
How do you control environmental nuisance variables?
Difficult, but one solution is to hold them constant.
26
How do you calculate sMD?
sMD = sD/square root of n.