Presentation on theme: "Allyn & Bacon 2003 Social Work Research Methods: Qualitative and Quantitative Approaches Topic 7: Basics of Measurement Examine Measurement."— Presentation transcript:
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Copyright @ Allyn & Bacon 2003 Topic7: Basics of Measurement Why measure? What are the differences between qualitative and quantitative measurement? What is Operationalization? What is Reliability? What is Validity? What are the four Levels of measurement? What are indices and scales? What is involved in Index construction? What is involved in Scale Construction?
Copyright @ Allyn & Bacon 2003 Why Measure? Measurement is the assignment of a symbol, often a numeral, to represent an object. Scientific measurement extends our senses. By using telescopes, microscopes or standardized scales we obtain more exact information, often seeing things that would otherwise have been invisible. It is important to have a clear idea about what is intended to be measured.
Copyright @ Allyn & Bacon 2003 What are the differences between Qualitative and Quantitative Measurement? While planning and designing precise ways to measure is critical to quantitative social work researchers, qualitative researchers are more likely to design their own strategies as they go. Quantitative researchers develop techniques that produce quantitative or numerical data; qualitative researchers are more likely to use words, symbols, pictures and physical objects as data. Quantitative social work researchers contemplate concepts and variables prior to conducting the research or evaluation, whereas qualitative researchers develop their measurements as they go.
Copyright @ Allyn & Bacon 2003 What is Operationalization? Quantitative social work researchers operationalize variables by turning conceptual definitions into a set of procedures to be used in collecting data. Qualitative social work researchers operationalize on the fly as they proceed through the research experience and think about what they are doing in concert with others who are also present in the setting.
Copyright @ Allyn & Bacon 2003 What is Reliability? Reliability refers to the dependability or consistency of a measurement instrument. Stability reliability is its consistency over time. Representative reliability is its consistency across subpopulations. Equivalence reliability is its consistency obtained from using multiple measures. Reliability can be improved by clearly conceptualizing concepts, increasing the levels of measurement and using multiple indicators of a variable.
Copyright @ Allyn & Bacon 2003 What is Validity? Validity is the accuracy of a measuring instrument. Face validity is the judgment of experts about a scale or instrument. Content validity is the extent to which the full content of the concept is represented in any particular measurement.
Copyright @ Allyn & Bacon 2003 Validity continued… Criterion validity is the extent to which an instrument compares favorably with some other instrument of known validity. It may be either concurrent or predictive. Construct validity is for measures with multiple indicators, to examine whether the various indicators operate consistently. It may be either convergent or discriminant.
Copyright @ Allyn & Bacon 2003 What are the Four Levels of Measurement? Nominal measurements are mutually exclusive and exhaustive categories. Ordinal measurements are mutually exclusive and exhaustive categories that are ranked. Interval measurements are mutually exclusive and exhaustive categories that are ranked with equal distance between the categories being measured. Ratio measurements are mutually exclusive and exhaustive categories that are ranked with equal distance between categories being measured, and there is a true zero.
Copyright @ Allyn & Bacon 2003 Indices and Scales in Social Work Research An index is a measure in which a social work researcher adds or combines several distinct indicators or constructs into a single score. A scale is a measure in which a social work researcher captures the intensity, direction, level, or potency of a variable construct, arranging responses on a continuum.
Copyright @ Allyn & Bacon 2003 What is involved in Index Construction? Develop a set of questions on the same topic. Decide whether to weight each item. Decide how to handle missing data. Decide whether to use rates and standardization.
Copyright @ Allyn & Bacon 2003 What is involved in Scale Construction? The Likert Scale is called a summated rating or additive scale because a total score is computed along a continuum such as: I really like research methods, with the choices being: SA A Unc D SD Thurstone Scale consists of many statements that are rated by judges to reduce a number of items to a range that spans all opinions on the topic. Bogardus Social Distance involves responses that are gathered into a series of ordered statements from very threatening to least threatening.
Copyright @ Allyn & Bacon 2003 Scales continued…. Semantic Differential involves responses that are gathered to a set of polar opposite adjectives that create a rating scale. Bad __ __ __ __ __ Good Fast __ __ __ __ __ Slow The Guttman Scaling is called cumulative scaling. This is a technique researchers use after data have been collected to determine whether a set of items can be combined to form a scale.