Singlefactor Multilevel design

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Single-factor Multi-level design
Research Methods Part III Lecture 18
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Single-factor, Multilevel designs

• One independent variable and more than two levels

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Aschs conformity study (1956)
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Social Influence

• Aschs conformity experiments

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Social Influence
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Aschs conformity study (1956)
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Single-factor, Multilevel designs - Examples
Darley Latané (1968) 1, 2, 5 conditions
(levels)
Epileptic Seizure
A
B
C
F
D
E
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Darley Latané (1968)
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Single-factor, Multilevel designs

• advantages
• be able to explore a trend including nonlinear
  effects

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Arousal and task performance
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Single-factor, Multilevel designs

• advantages
• be able to explore a trend - nonlinear effects
• it can be used for testing specific alternative
  hypotheses simultaneously
• e.g., memory and context (Bransford Johnson,
  1972)
• how we comprehend new information? context
  effect!

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• If the balloons popped, the sound wouldnt be
  able to carry, since everything would be too far
  away from the correct floor. A closed window
  would also prevent the sound from carrying, since
  most buildings tend to be well insulated. Since
  the whole operation depends on a steady flow of
  electricity, a break in the middle of the wire
  would also cause problem. Of course, the fellow
  could shout, but the human voice is not loud
  enough to carry that far. An additional problem
  is that a string could break on the instrument.
  Then there could be no accompaniment to the
  message. It is clear that the best situation
  would involve less distance. Then there would be
  fewer potential problems. With face to face
  contact, the least number of things could go
  wrong.

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Memory and Context (Bradford Johnson, 1972)
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B
A
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Memory and Context (Bradford Johnson, 1972)
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Presenting data using graphs

• Types of variables
• continuous vs. discrete variable
• continuous variable
• its values are on a continuum

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Line vs. Bar graphs

• Discrete variable - each value represent a
  distinct category and no intermediate points

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How to analyze the data?

• Analysis of variance (ANOVA)
• one-way ANOVA
• Simultaneously compare the mean differences among
  more than two groups
• basic idea

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ANOVA
Total variance
Total variance
B
B
W
W
F ratio is small
F ratio is big
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Subsequent analyses

• Overall F test
• planned vs. post hoc (after the fact) analysis

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Single-factor, Multilevel designs

• within-subjects designs
• repeated measure
• example a hypothetical longitudinal study
  examining the effect of age on logical thinking
• 7 individuals
• measured 3 times (age 30, 45, 60)

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Logical reasoning test
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Logical reasoning test
60
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Within-Subjects Single-Factor Design

• Analysis of variance (ANOVA) for repeated
  measures
• basic idea