Lecture   7   measurement ii
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Lecture 7 measurement ii

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Lecture   7   measurement ii Lecture 7 measurement ii Presentation Transcript

  • # 7 Location In The Research Process
    Formulating
    Research
    Questions
    Appropriate
    Design
    Craft
    Knowledge
    Appropriate
    Sampling
    Decisions
    Previous
    Research
    Ensure
    Research
    Ethics
    Data
    Collection
    &
    Management
    Data
    Analysis
    Ongoing
    Research
    Interpretation
    Dissemination
  • Measurement II
    What did we catch?
    Was it the same as the others?
    How do we know we caught it?
  • Properties of Instruments
    Reliability
    The stability and consistency of a measure
    Validity
    How we know that our measure captures what we're interested in
  • AN INSTRUMENT MUST HAVE RELIABILITY BEFORE IT CAN HAVE VALIDITY!
  • Reliability
    The stability and consistency of an instrument
    Stability
    Similar results over time
    Consistency
    Test items will be consistent with each other
    Items will be consistent with the overall score on the test
  • Stability
    Measured using test-retest reliability checks
    A participant completes the test at one point in time
    After a period of time elapses they complete the test again
    Usually at least 6 weeks
    Assessed using correlation coefficients
    Pearson r
    Spearman 
  • Consistency
    Internal consistency
    The items all measure the same core construct
    Measured using the Cronbach's Alpha Coefficient 
    A form of multiple correlation
    Measures how much the individual items in a test or scale have in common statistically
  • First Question
    The Juvenile Court Administrator wants to evaluate a new assessment tool to find out if you can tell which kids, once released from Detention, will recidivate or not.
    What is the first thing that must be done to solve your groups research problem?
    How do you propose to do it?
  • Validity
    How we know that our instrument captures what we're interested in
    Concept translation
    How well our instrument translates a concept into a variable
    Validity is reported as correlations of varying complexity
  • Validity
    Face Validity
    Convergent / Concurrent Validity
    Discriminant Validity
    Predictive Validity
  • Face Validity
    How well an instrument apparently accomplishes concept translation
    How completely an instrument samples all of the components of a concept
    Panels of experts
    In the domain being measured
    Who have experience with the target
  • Convergent / Concurrent Validity
    How well an instrument relates to other measures of the same or similar concepts
    Compare an instrument with:
    Other existing instruments
    Expert opinions
    Behavioral observations
    Assessed when the measure is given to subjects
  • Discriminant Validity
    How well an instrument discriminates between the presence or absence of concept components
    An instrument can discriminate between known groups, assessed when the measure is given to subjects
  • Predictive Validity
    How well an instrument predicts future events or behavior
    Useful concepts will predict phenomena
    Predictive validity assessment - examines how we know that our measure captures what we are interested in
    Compare the instrument with other predictive factors
    Test prediction of the measure alone
    Assessed longitudinally, after the instrument is given to subjects
  • Second Question
    The DCFS Area Regional Director wants to be able to tell how many future CPS referrals families are likely to have after their first CPS referral. He devises a questionnaire for the child’s mother to complete.
    What type of validity is involved in your research problem?
    What data might you use to address the validity question?