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Measuring variables unit 4

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  • 1. Measuring Variables SARISA BORIPET 55810262 KHANITTA MEEPRADIT 5581025028/01/13 1
  • 2. Outline • An Overview of Measurement • Constructs and Operational Definitions • Validity and Reliability of Measurement • Scales of Measurement • Modalities of Measurement • Other Aspects of Measurement28/01/13 2
  • 3. An Overview Of Measurement • The research process – Find an unanswer question – Forming a hypothesis – Developing a research study – Defining and measuring the variables • Variables : characteristics or conditions that change or have different values for different individuals28/01/13 3
  • 4. Aspects of measurement• Not a one to one relationship – Variable being measured : Measurements obtained• Usually several different options for measuring particular variable28/01/13 4
  • 5. Example Measure Knowledge for each student Impossible to look inside each student’ head An An exam essay A set of problems28/01/13 5
  • 6. The selection of a measurement procedure• The general process of measurement• The different measurement options• The consequences of each option28/01/13 6
  • 7. Constructs And Operational Definitions• Constructs Definitions• Operational Definitions28/01/13 7
  • 8. Constructs Definitions• Hypothetical attributes or mechanisms that help explain and predict behavior in a theory External External Constructs Stimulus behavior28/01/13 8
  • 9. Operational Definitions• A procedure for measuring and defining a construct Definition and Measurement of Definition and Measurement of the hypothetical construct the hypothetical construct28/01/13 9
  • 10. Example : Operational Definitions Intelligence IQ Hunger ?28/01/13 10
  • 11. Using Operational Definitions A research study are hypothetical constructs28/01/13 11
  • 12. Outline • An Overview of Measurement • Constructs and Operational Definitions • Validity and Reliability of Measurement • Scales of Measurement • Modalities of Measurement • Other Aspects of Measurement28/01/13 12
  • 13. Validity and Reliability of Measurement• Validity of Measurement• Definitions of Validity• Reliability of Measurement – Type and Measures of Reliability• The Relationship Between Reliability and Validity28/01/13 13
  • 14. Validity of Measurement• Validity : first criterion for evaluation a measurement procedure• Definition – The validity of a measurement procedure is the degree to which the measurement process measures the variable that it claims to measure.28/01/13 14
  • 15. Methods for Assessing the Validity of Measurement• Face Validity• Concurrent Validity• Consistency of a Relationship• Predictive Validity• Construct Validity• Convergent and Divergent Validity28/01/13 15
  • 16. Face Validity• Definition of Face Validity : Simplest and least scientific• Concerns the superficial appearance IQ Test Logic, reasoning, background knowledge, good memory Intelligence28/01/13 16
  • 17. Concurrent Validity• The scores obtained from the new measurement technique are directly related to the scores obtained from another28/01/13 17
  • 18. Consistency of a Relationship• The validity (and reliability) of measurement a can be established by demonstrating the consistency of a relationship between two different measurements Test of IQ Test of IQ Score from a STANDARDIZE IQ test Relationship Score from a NEW IQ test28/01/13 18
  • 19. Scatter Plots Showing Different Relationships Positive Relationship Negative Relationship28/01/13 No Consistent Relationship 19
  • 20. Predictive Validity• Theories predict how difference values of a construct affect behavior• The measurement of a construct accurately predict according to the theory28/01/13 20
  • 21. Construct Validity• The demonstrate that measurements of a specific variable behave in exactly the same way as the past research28/01/13 21
  • 22. Convergent and Divergent Validity • Convergent Validity is demonstrated by a strong relationship between the scores obtains from two difference methods of measuring the same construct • Divergent Validity is demonstrated by using two different methods to measure two different constructs. Then there should be little or no relationship between the scores28/01/13 22
  • 23. Validity and Reliability of Measurement• Validity of Measurement• Definitions of Validity• Reliability of Measurement – Type and Measures of Reliability• The Relationship Between Reliability and Validity28/01/13 23
  • 24. Reliability of Measurement• The second criterion for evaluating the quality of a measurement procedure• Reliability : Repeatedly to measure the same individual under the same condition, should nearly28/01/13 24
  • 25. Concept of Reliability Should average to ZERO Measured Score = True Score + Error28/01/13 25
  • 26. Sources of Error• Observer Error• Environment Error• Participant Error example Test of intelligence IQ test28/01/13 26
  • 27. Type and Measures of Reliability• Successive measurement• Simultaneous measurement• Internal consistency28/01/13 27
  • 28. Type and Measures of Reliability • Successive measurement • A researcher may use exactly the same measurement procedure for the same group of individuals at two different times • Called Test - Retest reliability • Simultaneous measurement • Measurements are obtained by direct observation of behaviors, it is common to use two or more separate observers who simultaneously record measurement • Called inter-rater reliability28/01/13 28
  • 29. Type and Measures of Reliability• Successive measurement• Simultaneous measurement• Internal consistency • General process results : Split-half reliability Example : 1. Use multiple-exams to measure performance in an academic course 2. Splitting the exams in half 3. Then calculating the degree of consistency between the two scores for a group of participants28/01/13 29
  • 30. The Relationship Between Reliability and Validity• Both : Criteria for evaluation the quality measurement procedure• Partially related and Partially independent – Related : Reliability is a prerequisite for validity – independent : Not necessary for a measure to be valid for to be reliable28/01/13 30
  • 31. Outline • An Overview of Measurement • Constructs and Operational Definitions • Validity and Reliability of Measurement • Scales of Measurement • Modalities of Measurement • Other Aspects of Measurement To be Continue28/01/13 31