Introduction to Measurement
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Introduction to Measurement

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Lecture from class on Measurement

Lecture from class on Measurement

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Introduction to Measurement Introduction to Measurement Presentation Transcript

  • Measuring Anything
    Purposes of ResearchMeasurement and Conceptualization
    Levels of Measurement
  • Purposes of Social Research
    Mapping out a topic that may warrant further study later
    Looking into a new political group.
    Describing the state of social affairs:
    What is the unemployment rate?
    Providing reasons for phenomena, in terms of causal relationships:
    Why do some cities have higher unemployment rates than others?
    Both our measurement approach and our research design will be influenced by our purpose.
  • Measurement
    Careful, deliberate observations of the real world for the purpose of describing objects and events in terms of the attributes composing a variable.
    Measurement may be applied to
    Facts
    Constructs
    (learn those definitions now if you don’t have them memorized already!!)
  • Qualitative and Quantitative
    Qualitative Data - Nonnumerical data.
    Often found in exploratory studies
    Included in nearly all studies
    Quantitative Data - Numerical data.
    Makes observations more explicit and makes it easier to aggregate, compare, and summarize data.
  • Pure and Applied Research
    Pure Research - Sometimes justified in terms of gaining “knowledge for knowledge’s sake.”
    Can be quantitative or qualitative
    Can be exploratory, descriptive, or analytical
    Applied Research - Putting research into practice.
    Can be quantitative or qualitative
    More likely to be analytical, or at least descriptive
  • Conceptualization
    Especially important with constructs
    Process of specifying what we mean when we use particular terms.
    Produces an agreed upon meaning for a concept for the purposes of research.
    Describes the indicators we'll use to measure the concept and the different aspects of the concept.
  • Indicators
    An observation that we choose to consider as a reflection of a constructwe wish to use as a variable in our study.
    For example, attending religious services might be considered an indicator of the construct called “religiosity.”
  • Dimension
    A specifiable aspect of a concept.
    “Religiosity,” for example, might be specified in terms of a
    belief dimension,
    a ritual dimension,
    a devotional dimension,
    a knowledge dimension,
    a financial dimension
    …and so forth.
  • Interchangeability of Indicators
    If different indicators all represent the same construct, they behave the way the concept would behave if it could be observed.
    If women are more compassionate, we should be able to observe that using a reasonable measure of compassion.
    If women are more compassionate on some indicators but not on others, the various indicators probably represent different dimensions of compassion.
  • Specification of Concepts
    The specification of constructs in scientific inquiry depends on nominal and operational definitions.
    A nominal definition is assigned to a term without any claim that the definition represents a “real” entity.
    An operational definition specifies how a concept will be measured—that is, the operations we’ll perform.
  • Definitions
    Real (Reification)-mistakes a construct for a real entity.
    Nominal - assigned to a term without a claim that the definition represents a "real" entity.
    Operational definitions- Specifies how a concept will be measured.
  • Construct to Measurement
    Progression from what a term means to measurement in a scientific study:
    Conceptualization
    Nominal Definition
    Operational Definition
    Measurements in the Real World
    In published research
    The literature review presents a conceptualization
    The Method section describes the operational definition(s) used to create the variable(s)
  • NominalScale/Level of Measurement
    A level of measurement describing a variable that has attributes that are merely different, as distinguished from ordinal, interval, or ratio measures.
    Gender is an example of a nominal measure.
  • OrdinalScale/Level of Measurement Measure
    A level of measurement describing a variable with attributes we can rank-order along some dimension.
    An example is socioeconomic status as composed of the attributes high, medium, low.
  • IntervalScale/Level of Measurement Measures
    A level of measurement describing a variable whose attributes are rank-ordered and have equal distances between adjacent attributes.
    The Fahrenheit temperature scale is an example of this, because the distance between 17 and 18 is the same as that between 89 and 90.
    IQ does not have an absolute zero
  • RatioScale/Level of Measurement Measures
    A level of measurement describing a variable with attributes that have all the qualities of nominal, ordinal, and interval measures and are based on a “true zero” point.
    Examples: Age, Cash you are carrying,Number of siblings, GPA
  • Kaplan’s Classes
    Things Scientists Measure
    Direct observables - things that can be observed simply and directly.
    Indirect observables - things that require more subtle observations.
    Constructs - based on observations that cannot be observed.
  • Measurement Quality
    Precision and accuracy
    Reliability
    Validity
  • Reliability
    Quality of measurement method that suggests the same data would have been collected in repeated observations.
    The question “Did you attend religious services last week?” would have higher reliability than “About how many times have you attended religious services in your life?”
  • Tests for Checking Reliability
    Test-retest method - take the same measurement more than once.
    Split-half method - make more than one measurement of a social concept (prejudice).
    Use established measures.
    Check reliability of research-workers.
  • Validity
    A term describing a measure that accurately reflects the concept it is intended to measure.
    Example: IQ would seem a more valid measure of intelligence than the number of hours spent in the library.
    Relative validity can be determined on the basis of face validity, criterion validity, content validity, construct validity, internal validation, and external validation.
  • Face Validity
    That quality of an indicator that makes it seem a reasonable measure of some variable.
    That the frequency of attendance at religious services is some indication of a person’s religiosity seems to make sense without a lot of explanation.
  • Construct and Content Validity
    Construct Validity
    The degree to which a measure relates to other variables as expected within a system of theoretical relationships.
    Content Validity
    Refers to how much a measure covers the range of meanings included within a concept.
  • Ethics of Measurement
    Most of the concepts of interest to social researchers are open to varied meanings.
    If personal bias made you want to minimize support for a position, you might be tempted to frame the concept and the measurements based on it in biased terms violating accepted research ethics.