PS28C Psychometrics

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PS28CPsychometrics

• Tutorial 3
• Defining Your Construct

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Introduction

• Tutorial will teach
• How to define your construct
• The importance of properly defining your
  construct
• How to find information on your construct using
  Library databases and the internet

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Introduction

• Three exercises on developing your construct
• Defining your construct
• Searching for information on your construct
• Refining your construct

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Defining Your Construct

• Most important task in creating a scale is
  defining the construct
• Must define the construct in detail
• Most constructs are theoretical abstractions
• Challenge is to operationally define the construct

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Defining Your Construct

• Must fit your construct into a network of
  relationships with other constructs
• Need to determine
• What your construct is similar to
• What your construct is different from

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Defining Your Construct

• Most problems due to failure to adequately define
  construct
• Often due to familiarity with construct
• Should follow an inductive approach to defining
  your construct
• Start with a clear definition of the construct

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Defining Your Construct

• Need a detailed listing of
• What the construct is related to
• What the construct is different from
• Listing will create a network of relationships
  called a nomothetic network
• Network leads to hypotheses that will be tested
  by your study

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Exercise 1Defining Your Construct

• Task is to develop a listing of the features of
  your construct
• Identify what your construct is similar to
• Identify what your construct is different from
• Should create a detailed listing of the features
  of your construct

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Finding Information on Your Construct

• First step is to conduct an extensive search of
  past research
• Look for theoretical discussions of your
  construct
• Search for existing scales assessing your
  construct
• May help to further refine your constuct
• May serve as an initial pool of items

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Finding Information on Your Construct

• Good source of past research is librarys
  databases of journals
• EBSCO ProQuest most useful
• Population lab has one license for APAs
  PsychArticles
• Researchers very willing to help
• Find e-mail address of researchers on their papers

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Exercise 2Using the Library Databases

• Search for past research on your construct using
  EBSCO or ProQuest
• Identify at least 4 papers related to your
  construct
• Identify researchers who have done research on
  your construct

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Refining Your Construct

• Constructs can be simple or complex
• Simple constructs can require only 1 item
• Complex constructs require many items to assess
  all aspects
• Clusters of items which assess the same aspect
  called sub-scales

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Refining Your Construct

• Constructs can be homogenous
• All aspects relate to the same property
• Constructs can be heterogeneous
• Several aspects with each assessing slightly
  different features
• Need to decide if your construct is
• Simple or complex
• Homogenous or heterogenous

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Refining Your Construct

• Decision should be based on theoretical and
  empirical utility
• Need to follow scientific principal of simplier
  is better than complex

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Exercise 3Refining Your Construct

• Decide whether your construct is simple or
  complex
• Determine if your construct is homogenous or
  heterogenous
• Based your decision on literature and empirical
  justifications