Chapter 4: Measurement Next time: Statistics Chapter 8

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Chapter 4 MeasurementNext time Statistics
(Chapter 8)
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University of FloridaPsychology ClubPsi Chi
Honor Society

• FIRST MEETING IS THURSDAY, JAN. 24
• _at_ 720 IN NPB1001!
• Meeting Schedule
• 1/24, 2/7, 2/21, 3/6,
• 3/20, 4/3 and 4/17
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I have been meaning to tell you to spread the
word down in the psych department that Div 41 of
APA (Psychology-Law) is having our annual meeting
in Jax this year from March 5th -8th
http//www.ap-ls.org/conferences/apls2008/index.ht
ml We probably still need some student
volunteers (they get free registration if they
work enough hours) for Tuesday and Wednesday
before the conference officially starts.  If you
know of any who are interested, send them my way.

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Chapter 4 MeasurementNext time Statistics
(Chapter 8)
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Operational definition Definition of a variable
in terms of the operations used to produce or
measure the variable
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Level of Measurement

• Nominal
• Ordinal
• Interval
• Ratio

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Decisions about Measurement

• How to operationalize
• Which aspects (e.g., frequency, intensity,
  duration)
• Context (field, lab)
• Source (behavior, verbal report)
• Goal (state-trait)

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ReliabilityValidity
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Reliability Consistency or repeatability of
measurement
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Reliability

• Test-Retest
• Internal Consistency

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Test validity Accuracy with which a test
measures what it is supposed to measure
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Forms of Test Validity

• Content validity
• Criterion validity
• Construct validity

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Convergent Validity
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Convergent ValidityDivergent Validity
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Shared methods variance Similarity among two or
more sets of scores that results from
similarities in the methods used to obtain the
scores
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Multitrait-Multimethod (MTMM) Matrix
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Trait A B C
1 A1 B1 C1 Method 2 A2 B2
C2 3 A3 B3 C3
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RegressionToward the Mean
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Regression toward the mean Tendency of initially
extreme scores to move toward the group mean upon
retesting
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Threats to Validity in Pretest-Posttest Designs

• Regression toward the mean
• Testing
• History
• Maturation

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Mean Time 1 Time 2

• Grads 105 97 ?
• Dropouts 90 97 ?