Psychometric Properties and Principles

Psychometric properties refer to the characteristics of a psychological test that determine its reliability and validity. These properties include:

• Reliability (consistency of results).
  • Test-Retest Reliability: Measures the consistency of results when the same test is administered to the same group of individuals at different times.
  • Inter-Rater Reliability: Measures the agreement between different raters or observers when assessing the same phenomenon.
  • Internal Consistency Reliability: Measures the extent to which items within a test or scale are consistent in measuring the same construct.
  • Parallel Forms Reliability: Measures the consistency of results between different versions of the same test.
  • Split-Half Reliability: Measures the consistency of results by splitting a test into two halves and comparing the scores.
• Validity (accuracy of measuring what it intends to measure)
  • Internal Validity: Refers to the extent to which a study accurately measures the cause-and-effect relationship between variables within a controlled setting.
  • External Validity: Relates to the generalizability of research findings to the real world or other populations.
  • Construct Validity: Involves the degree to which a measurement accurately assesses the theoretical construct it intends to measure.
  • Content Validity: Refers to the extent to which a measurement covers all relevant aspects of the construct being measured.
  • Criterion Validity: Assesses the degree to which a measurement correlates with an established criterion or gold standard.
  • Concurrent Validity: Measures the extent to which a new measurement correlates with an existing measurement of the same construct.
  • Predictive Validity: Determines the extent to which a measurement predicts future outcomes or behaviors.
  • Face Validity: Involves the subjective judgment of whether a measurement appears to measure what it intends to measure.
• Standardization (consistent administration and scoring): In psychometric properties, standardization refers to the process of administering a test using standardized protocols. This means that the test is carefully developed and administered in a consistent manner to ensure that the results are reliable and valid.
• Norms (comparison to a representative sample): Norms, on the other hand, are an integral aspect of psychological testing and provide context and interpretation to test scores. They are established by administering a psychological test to a representative sample of individuals and then comparing their scores to determine the average or typical performance for a particular group. Norms provide a basis for comparing an individual’s test score with the scores of others in the same group.

Principles of psychometrics involve the use of statistical methods to analyze test data, such as:

• Item analysis

  • It is a statistical technique used in educational assessment to evaluate the quality of test items. It helps identify the effectiveness of individual test questions and provides insights into student performance. There are two main types of item analysis:
  1. Difficulty Index: Measures the proportion of students who answered an item correctly. It helps determine the level of difficulty of an item and its ability to discriminate between high and low-performing students.
  2. Discrimination Index: Assesses the ability of an item to differentiate between high and low-performing students. It compares the performance of students who scored well on the overall test with those who scored poorly.

• Factor analysis

  • It is a statistical method used to identify underlying factors or dimensions within a set of observed variables. It aims to reduce the complexity of data by grouping variables that are highly correlated. There are two main types of factor analysis:
  1. Exploratory Factor Analysis (EFA): EFA is used when the researcher does not have a pre-defined hypothesis about the underlying factors. It helps in identifying the number of factors and their composition.
  2. Confirmatory Factor Analysis (CFA): CFA is used when the researcher has a pre-defined hypothesis about the underlying factors. It tests the fit of the data to the hypothesized factor structure.

• Test equating

  • It is a statistical process used to adjust scores from different versions or forms of a test to ensure comparability. It aims to account for differences in difficulty between test forms and establish a common scale for score interpretation.

  There are three main types of test equating methods:

  1. Concurrent Equating: This method involves administering two or more test forms to the same group of examinees simultaneously. The scores on the different forms are then equated using statistical techniques.
  2. Post-equating: This method is used when the test forms are administered to different groups of examinees at different times. The scores on the different forms are equated by using a common reference group that has taken both forms.
  3. Anchor Test Equating: This method involves including a set of anchor items that are common to both test forms. The scores on the anchor items are used to establish a link between the two forms, allowing for equating of the scores.