Construct Validity: A Universal Validity System

1. Construct Validity: A Universal Validity System Susan Embretson Georgia Institute of Technology

2. Introduction • Validity is a controversial concept in educational and psychological testing • Research on educational and psychological tests during the last half of the 20th century was guided by distinction of types of validity • Criterion-related validity, content validity and construct validity • Construct validity is the most problematic type of validity • It involves theory and the relationship of data to theory

3. Introduction • Yet the most controversial type of validity became the sole type of validity in the revised joint standards for educational and psychological tests (AERA/APA/NCME, 1999) • In the current standards “Validity refers to the degree to which evidence and theory support the interpretations of test scores entailed by proposed uses of test” • Content validity and criterion-related validity are two of five different kinds of evidence. • Reflects substantial impact from Messick’s (1989) thesis of a single type of validity (construct validity) with several different aspects.

4. Topics Overview of the validity concept Current issues on validity Discontent with construct validity for educational tests Need for content validity Critique of content validity as basis for educational testing Universal system for construct validity Applies to all tests Achievement tests Ability tests Personality/psychopathology Summary

5. History of the Construct Validity Concept: Origins • American Psychological Association (1954). Technical recommendations for psychological tests and diagnostic techniques. Psychological Bulletin, 51, 2, 1-38. • Prepared by a joint committee of the American Psychological Association, American Educational Research Association, and National Council on Measurements Used in Education. • “Validity information indicates to the test user the degree to which the test is capable of achieving certain aims. … “Thus, a vocabulary test might be used simply as a measure of present vocabulary, as a predictor of college success, as a means of discriminating schizophrenics from organics, or as a means of making inferences about "intellectual capacity.“ • “We can distinguish among the four types of validity by noting that each involves a different emphasis on the criterion. (p. 13)

6. History of the Construct Validity Concept: Origins Types of validity by use Content validity “The test user wishes to determine how an individual would perform at present in a given universe of situations of which the test situation constitutes a sample.” Predictive validity “The test user wishes to predict an individual's future performance.” Concurrent validity “The test user wishes to estimate an individual's present status on some variable external to the test.” Construct validity “The test user wishes to infer the degree to which the individual possesses some trait or quality (construct) presumed to be reflected in the test performance.”

7. History of the Construct Validity Concept: Origins Cronbach, L. J. & Meehl, P. E. (1955). Construct validity in psychological tests. Psychological Bulletin, 52, 281-302. “We can dsitinguish among four types of validity by noting that each one puts a different emphasis on the criterion. In predictive or concurrent, the criterion behavior is of concern to the tester and he may have no concern whatever with the type of behavior observed on the test” “ Content validity is studied when the tester is concerned with the type of behavior in the test performance. Indeed, if the test is a work sample, the test may be an end in itself.” “Construct validity is ordinarily studied when the tester has no definite criterion measure of the quality with which he is concerned, and must use indirect measures. Here the trait or quality underlyng the test is of central importance…….”

8. Implications of Original Views • Same test can be used in different ways • Relevant type of validity depends on test use • The types of validity differ in the importance of the behaviors involved in the test

9. More Recent Views on Types of Validity • Standards for Educational and Psychological Testing (1954; 1966; 1974, 1985, 1999) • 1985 • “Traditionally, the various means of accumulating validity evidence have been grouped into categories called content-related, criterion-related and construct-related evidence of validity. …” “These categories are convenient.…but the use of category labels does not imply that there are distinct types of validity…” • “An ideal validation includes several types of evidence, which span all three of the traditional categories.”

10. Conceptualizations of Validity: Psychological Testing Textbooks • “All validity analyses address the same basic question: Does the test measure knowledge and characteristics that are appropriate to its purpose. There are three types of validity analysis, each answering this question in a slight different way.” (Friedenberg,1995) • “ …..the types of validity are potentially independent of one another.” (Murphy & Davidshofer,1988) • “There are three types of evidence: (1) construct-related, (2) criterion-related, and (3) content-related.” …..”It is important to emphasize that categories for grouping different types of validity are convenient; however, the use of categories does not imply that there are distinct forms of validity.” Kaplan & Saccuszzo (1993)

11. Most Recent View on Types of Validity • Standards for Educational and Psychological Testing 1999 • “Validity refers to the degee to which evidence and theory support the interpretations of test scores entailed by proposed uses of tests”. The proposed interpretation refers to the construct or concepts that the test is intended to represent.” (p.9) • “These sources of evidence may illuminate different aspects of validity, but they do not represent distinct types of validity. Validity is a unitary concept.” • “The wide variety of tests and circumstances makes it natural that some types of evidence will be especially critical in a given case, whereas other type will be less useful.” (p. 9) • “Because a validity argument typically depends on more than one proposition, strong evidence in support of one in no way diminishes the need for evidence to support others. (p. 11).

12. The Sources of Validity Evidence Evidence based on test content Logical & empirical analysis of adequacy representing a content domain -- Includes themes, wording, item format and procedures for administration & scoring Evidence based on response processes Theoretical and empirical analysis of test taker’s response process with respect to construct Evidence based on internal structure Relationships among test items correspond to construct structure Evidence based on relations to other variables Convergent & discriminate evidence Test-criterion relationships Validity generalization Evidence based on the consequences of testing Different impact by group, claims of testing benefits

13. Implications of 1999 Validity Concept No distinct types of validity Multiple sources of evidence for single test aim Example-Mathematical achievement test used to assess readiness for more advanced course Propositions for inference 1) Certain skills are prerequisite for advanced course 2) Content domain structure for the test represents skills 3) Test scores represent domain performance 4) Test scores are not unduly influenced by irrelevant variables, such as writing ability, spatial ability, anxiety etc. 5) Success in advanced course can be assessed 6) Test scores are related to success in advanced curriculum

14. Current Issues with the Validity Concept: Educational Testing Crocker (2003) Content aspect of validity deserves more prominence Educational accountability needs content representativeness More methods for content related evidence needed Design-- test specification and item generation; Item review tasks; Subject matter expert reliability Data analysis techniques for content judgments Fremer (2000) Construct validity is an unreachable goal Borsboom, Mellenbergh & van Heerden (2004) Current validity theory “fails to serve either the theoretically oriented psychologist or the practically inclined tester”

15. Current Issues with the Validity Concept: Educational Testing • Lissitz and Samuelson (2007) • Propose some changes in terminology and emphasis in the validity concept • Argue that “construct validity as it currently exists has little to offer test construction in educational testing”. • In fact, their system leads to a most startling conclusion • Construct validity is irrelevant to defining what is measured by an educational test!! • Content validity becomes primary in determining what an educational test measures

16. Current Issues with the Validity Concept: Educational Testing Several published responses in Educational Researcher Embretson, S. E. (2007).Construct validity: A universal validity system or just another test Evaluation Procedure? Educational Researcher, Vol. 36, No. 8, pp. 449–455. Lissitz’ response: Organize a conference!

17. Critique of Content Validity as Basis for Educational Testing • Content validity is not up to the burden of defining what is measured by a test • Relying on content validity evidence, as available in practice, to determine the meaning of educational tests could have detrimental impact on test quality • Giving content validity primacy for educational tests could lead to very different types and standards of evidence for educational and psychological tests

18. Validity in Educational Tests Response to Lissitz & Samuelson • Background • Embretson, S. E. (1983). Construct validity: Construct representation versus nomothetic span. Psychological Bulletin, 93, 179-197. • Construct representation • Establishes the meaning of test scores from Identifying the theoretical mechanisms that underlie test performance (i.e., the processes, strategies and knowledge) • Nomothetic span • Establishes the significance of test scores by Identifying the network of relationships of test scores with other variables

19. Validity in Lissitz and Samuelson’s Framework Taxonomy of test evaluation procedures 1) Investigative Focus Internal sources = analysis of the test and its items Provides evidence about what is measured External sources =relationship of test scores to other measures & criteria Provides evidence about impact, utility and trait theory 2) Perspective Theoretical orientation = concern with measuring traits Practical orientation = concern with measuring achievement

20. Figure 2. Taxonomy of Test Evaluation Procedures Perspective

21. Figure 1. The Structure of the Technical Evaluation of Educational Testing

22. Implications for Validity System represents best current practices Internal meaning (validity) established For educational tests, content and reliability evidence Evidence based on internal structure (i.e., reliability, etc.) Evidence based on test content For psychological tests, depends on latent processes Evidence based on response processes Evidence based on internal structure (item correlations) But, notice the limitations Response process and test content evidence are not relevant to both types of tests External evidence based on relations to other variables has no role in validity

23. External Evidence Only? • Construct validity is removed from the validity sphere! • Critical to this view of construct validity is classification as external evidence • However, Cronbach and Meehl’s conceptualization did include internal sources of evidence • Studies of internal structure • Studies of change • Studies of processes • Within the nomological network, these sources would be classified as test to construct evidence. • Thus, construct validity need not be decentralized for this reason

24. Current Practice of Construct Validity • However, internal sources of information have no priority in Cronbach and Meehl • Simply another sources of evidence • Considering only external sources may characterize some current practices • Re-conceptualize test meaning based on external evidence rather than develop new tests • Concern about the strong role of external sources motivated Embretson (1983) distinctions • If internal sources are primary, then item and test design principles can become central in establishing test validity (Embretson, 1995)

25. Construct Validity for Psychological Tests in a Revised Taxonomy • If construct validity included internal sources • Now crucial to meaning for psychological tests • Requires scientific foundation for item and test design principles • Impact of item features and testing procedures on KSAs • But, concept of construct validity still not relevant to include internal evidence for educational tests • Test meaning depends primarily on content-related evidence and reliability evidence

26. Internal Evidence for Educational Tests • Reliability concept in the Lissitz and Samuelson framework is generally multifaceted and traditional • Item interrelationships • Relationship of test scores over conditions or time • Differential item functioning (DIF) • Adverse impact • (Perhaps adverse impact and DIF could be considered as external information)

27. Internal Evidence for Educational Tests • Concept of Content Validity • Previous test standards (1985)** • Content validity was a type of evidence that “…..demonstrates the degree to which a sample of items, tasks or questions on a test are representative of some defined universe or domain of content” • Two important elements added by L&S • Cognitive complexity level • “whether the test covers the relevant instructional or content domain and the coverage is at the right level of cognitive complexity” • Test development procedures • Information about item writer credentials and quality control

28. Test Blueprints as Content Validity Evidence • Blueprints specify percentages of test items that should fall in various categories • Example- test blueprint for NAEP for mathematics • Five content strands • Three levels of complexity • Majority of states employ similar strands • But, several reasons why blueprints and other forms of test specifications (along with reliability evidence) are not sufficient to establish meaning for an educational test

29. 1. Domain Structure is a Theory Which Changes Over Time • NAEP framework, particularly for cognitive complexity, has evolved (NAGB, 2006) • Views on complexity level also may change based on empirical evidence, such as item difficulty modeling, task decomposition and other methods • Changes in domain structure also could evolve in response to recommendations of panels of experts. • National Mathematics Advisory Panel • Recommend changes in the basic strands

30. 2. Reliability of Classifications is Not Well Documented Scant evidence that items can be reliably classified into the blueprint categories Certain factors in an achievement domain may make these categorizations difficult For example, in mathematics a single real-world problem may involve algebra and number sense, as well as measurement content Item could be classified into three of the five strands. Similarly, classifying items for mathematical complexity also can be difficult Abstract definitions of the various levels in many systems

31. 3. Unrepresentative Samples from Domain • Practical limitations on testing conditions may lead to unrepresentative samples of the content domain • More objective item formats, such as multiple choice and limited constructed response have long been favored • Reliably and inexpensively scored • But these formats may not elicit the deeper levels of reasoning that experts believe should be assessed for the subject matter

32. 4. Irrelevant Item Solving Processes • Using content specifications, along with item writer credentials and item quality control, may not be sufficient to assure high quality tests • Leighton and Gierl (2007) view content specifications as one of three cognitive models for making inferences about examinee’s thinking processes • For the cognitive model of test specifications for inferences is that no evidence is provided that examinees are in fact using the presumed skills and knowledge to solve items

33. NAEP Validity Study for Mathematics: Grade 4 and Grade 8 • Mathematicians examined items from NAEP and some state accountability tests • Results • Small percent of items deemed flawedn(3-7%), • Larger percent of items deemed marginal (23-30%) • Marginal items had construct-irrelevant difficulties • problems with pattern specifications • unduly complicated presentation • unclear or misleading language • excessively time-consuming processes • Marginal items previously had survived both content-related and empirical methods of evaluation

34. Examples of Irrelevant Knowledge, Skills and Abilities • Source • National Mathematics Advisory Panel (2008). Foundations for success: The final report of the National Mathematics Advisory Panel. Washington, DC: Department of Education • Method- logical-theoretical analysis by mathematicians & curriculum experts • Mathematics involves aspects of logical analysis, spatial ability and verbal reasoning, yet their role can be excessive

35. Dependence on Non-Mathematical Knowledge

36. Dependence on Logic, Not Mathematics

37. Excessive Dependence on Spatial Ability

38. Excessive Dependence on Reasoning and Minimal Mathemataics

39. Implication for Educational Tests • Identifying irrelevant sources of item performance requires more than content-related evidence • Latent process evidence is relevant • E.g., methods include cognitive analysis (e.g., item difficulty modeling), verbal reports of examinees and factor analysis • External sources of evidence may provide needed safeguards • Example: Implications of the correlation of an algebra test with a test of English • If this correlation is too high, it may suggest a failure in the system of internal evidence that supports test meaning

40. Construct Validity as a Universal System and a Unifying Concept • Features • Consistent with current Test Standards (1999) • Consistent with many of Lissitz and Samuelson’s distinctions and elaborations • Validity Concept • Universal • All sources of evidence are included • Appropriate for both educational and psychological tests • Interactive • Evidence in one category is influenced or informed by adequacy in the other categories

41. Categories of Evidence in the Validity System • Eleven categories of evidence • Conceive the categories for application to both educational and psychological tests • Consistent with most validity frameworks and the current Test Standards (1999), it is postulated that tests differ in which categories in the system are most crucial to test meaning, depending on its intended use • Even so, most categories of evidence are potentially relevant to a test

42. A Universal Validity System Scoring Models Testing Conditions Item Design Principles Other Measures Latent Process Studies Test Specs Psycho- metric Properties Utility Logic/ Theory Domain Structure Impact Internal Meaning ExternalSignificance

43. Internal Categories of Evidence

44. Internal Categories of Evidence

45. External Categories of Evidence

46. The Universal System of Validity • Test Specifications is the most essential category: it determines (with Scoring Models) • Representation of domain structure • Psychometric properties of the test • External relationships of test scores • Preceding Test Specifications are categories that involve scientific evidence, knowledge and theory • Domain Structure • Item Design Principles • In turn preceded by • Latent Process Studies • Logical/Theoretical Analysis • Testing Conditions

47. General Features of Validity System • Test meaning is determined by internal sources of information • Test significance is determined by external sources of information • Content aspects of the test are central to test meaning • Test specifications, which includes test content and test development procedures, have a central role in determining test meaning • Test specifications also determine the psychometric properties of tests, including reliability information

48. General Features of the Universal Validity System • Broad system of evidence is relevant to support Test Specifications • Item Design Principles --Relevancy of examinees’ responses to the intended domain • Domain Structure --Regarded as a theory • Other preceding evidence • Latent Process Studies • Logical/theoretical analyses of the domain • Testing Conditions

49. General Features of the Universal Validity System • Interactions among components • Internal evidence  expectations for external • External evidence informs adequacy of evidence from internal sources • Potential inadequacies arise when • Hypotheses are not confirmed • Unintended consequences of test use • System of evidence includes both theoretical and practical elements • Relevant to educational and psychological tests

50. The Universal System of Validity • Example of Feedback • Speeded math test to emphasize automatic numerical processes • External evidence-- strong adverse impact • Internal evidence categories to question • Item Design • Relationship of item speededness to automaticity • Domain Structure • Heavy emphasis on the automaticity of numerical skills