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Test Worthiness. Chapter 3. Test Worthiness. Four cornerstones to test worthiness: Validity Reliability Practicality Cross-cultural Fairness But first, we must learn one statistical concept: Correlation Coefficient. Correlation Coefficient. Correlation –

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## Test Worthiness

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**Test Worthiness**Chapter 3**Test Worthiness**• Four cornerstones to test worthiness: • Validity • Reliability • Practicality • Cross-cultural Fairness • But first, we must learn one statistical concept: • Correlation Coefficient**Correlation Coefficient**• Correlation – • Statistical expression of the relationship between two sets of scores (or variables) • Positive correlation • Increase in one variable accompanied by increase in other • “Direct relationship” - They move in the same direction • Negative correlation • Increase in one variable accompanied by decrease in other • “Inverse relationship” – Variables move in opposite directions**Examples of Correlation Relationships**• What is the relationship between: • Gasoline prices and grocery prices? • Grocery prices and good weather? • Stress and depression? • Depression and job productivity? • Partying and grades? • Study time and grades?**Correlation (Cont’d)**• Correlation coefficient (r ) • A number between -1 and +1 that indicates direction and strength of the relationship • As “r” approaches +1, strength increases in a direct relationship (positive) • As “r” approaches -1, strength increases in an inverse relationship (negative) • As “r” approaches 0, the relationship is weak or non existent (at zero)**-1**0 +1 Strong Strong Weak Inverse Direct Correlation (cont) • Correlation coefficient “r” 0 to +.3 = weak +.4 to +.6 = medium +.7 to +1.0 = strong 0 to -.3 = weak -.4 to -.6 = medium -.7 to -1.0 = strong**Correlation Examples**r = .35 r = -.67**Correlation Scatterplots**• Plotting two sets of scores from the previous examples on a graph? • Place person A’s SAT score on the x-axis, and his/her GPA on the y-axis • Continue this for person B,C, D etc. • This process forms a “Scatterplot.”**What correlation (r ) do you think this graph has?**How about this correlation? Scatterplots (cont)**What might this correlation be?**This correlation? More Scatterplots**This correlation?**Last one More Scatterplots**Shared Trait Variance**Depression Anxiety Coefficient of Determination (Shared Variance) • The square of the correlation (r = .80, r2 = .64) • A statement about factors that underlie the variables that account for their relationship. • Correlation between depression and anxiety = .85. • Shared variance = .72. • What factors might underlie both depression and anxiety?**Validity**• What is validity? • The degree to which all accumulated evidence supports the intended interpretation of test scores for the intended purpose • Lay Def’n: Does a test measure what it is supposed to measure? • It is a unitary concept; however, there are 3 general types of validity evidence • Content Validity • Criterion-Related Validity • Construct Validity**Content Validity**• Is the content of the test valid for the kind of test it is? • Developers must show evidence that the domain was systematically analyzed and concepts are covered in correct proportion • Four-step process: • Step 1 - Survey the domain • Step 2 - Content of the test matches the above domain • Step 3 - Specific test items match the content • Step 4 - Analyze relative importance of each objective (weight)**Survey of Domain**Step 1: Survey the Domain Content Matches Domain Step 2: Content Matches Domain Step 3: Test items reflect content Item 1 x 3 Item 2 x 2 Item 3 x 1 Item 4 x 2 Item 5 x 2.5 Step 4: Adjusted for relative importance Content Validity (cont)**Content Validity (cont)**• Face Validity • Not a real type of content validity • A quick look at “face” value of questions • Sometimes, questions may not “seem” to measure the content, but do (e.g., panic disorder example in book (p. 48) • How might you show content validity for an instrument that measures depression?**Criterion-Related Validity: Concurrent and Predictive**Validity • Criterion-Related Validity • The relationship between the test and a criterion the test should be related to • Two types: • Concurrent Validity – Does the instrument relate to another criterion “now” (in the present)? • Predictive Validity – Does the instrument relate to another criterion in the future?**Criterion-Related Validity: Concurrent Validity**• Example 1 • 100 clients take the BDI • Correlate their scores with clinicians’ ratings of depression of the same group of clients. • Example 2 • 500 people take test of alcoholism tendency • Correlate their scores with how significant others rate the amount of alcohol they drink.**Criterion-Related Validity: Predictive Validity**• Examples: • SAT scores correlated with how well students do in college. • ASVAB scores correlated with success at jobs. • GREs correlated with success in graduate school. (See Table 3.1, p. 50) • Do Exercise 3.2, p. 49**Construct Validity**• Construct Validity • Extent to which the instrument measures a theoretical or hypothetical trait • Many counseling and psychological constructs are complex, ambiguous and not easily agreed upon: • Intelligence • Self-esteem • Empathy • Other personality characteristics**Construct Validity (cont)**• Four methods of gathering evidence for construct validity: • experimental design • factor analysis • convergence with other instruments • discrimination with other measures.**Construct Validity: Experimental Design**• Creating hypothesis and research studies that show the instrument captures the correct concept • Example: • Hypothesis: The “Blank” depression test will discriminate between clinically depressed clients and “normals.” • Method: • Identify 100 clinically depressed clients • Identify 100 “normals” • Show statistical analysis • Second Example: Clinicians measure their depressed clients before, then after, 6 months of treatment**Construct Validity: Factor Analysis**• Factor analysis: • Statistical relationship between subscales of test • How similar or different are the sub-scales? • Example: • Develop a depression test that has three subscales: self-esteem, suicidal ideation, hopelessness. • Correlate subscales correlate: • Self-esteem and suicidal ideation: .35 • Self-esteem and hopelessness: .25 • Hopelessness and suicidal ideation: .82 • What implications might the above scores have for this test?**Construct Validity: Convergent Validity**• Convergent Evidence – • Comparing test scores to other, well-established tests • Example: • Correlate new depression test against the BDI • Is there a good correlation between the two? • Implications if correlation is extremely high? (e.g., .96) • Implications if correlation is extremely low? (e.g., .21)**Construct Validity: Discriminant Validity**• Discriminant Evidence – • Correlate test scores with other tests that are different • Hope to find a meager correlation • Example: • Compare new depression test with an anxiety test. • Implications if correlation is extremely high? (e.g., .96) • Implications if correlation is extremely low? (e.g., .21)**Validity Recap**• Three types of validity • Content • Criterion • Concurrent • Predictive • Construct validity • Experimental • Factor Analysis • Convergent • Discriminant**Reliability**• Accuracy or consistency of test scores. • Would you score the same if you took the test over, and over, and over again? • Reported as a reliability(correlation) coeffiecient. • The closer to r = 1.0, the less error in the test.**Three Ways of Determining Reliability**• Test-Retest • Alternate, Parallel, or Equivalent Forms • Internal Consistency a. Coefficient Alpha b. Kuder-Richardson c. Split-half or Odd Even**A**A Time Test-Retest Reliability • Give the test twice to same group of people. • E.g. Take the first test in this class, and very soon after, take it again. Are the scores about the same? person 1person 2person 3person 4person 5 others…. • 1st test: 35 42 43 34 38 • 2nd test: 36 44 41 34 37 Graphic: • Problem: Person can look up answers between 1st and second testing**A**B Alternate, Parallel, or Equivalent Forms Reliability • Have two forms of same test • Give students two forms the same time • Correlate scores on first form with scores on second form. • Graphic: • Problem: Are two “equivalent” forms ever really equivalent?**Internal Consistency Reliability**• How do individual items relate to each other and the test as a whole? • Internal Consistency reliability is going “within” the test rather than using multiple administrations • High speed computers and only one test administration has made internal consistency popular • Three types: • Split-Half or Odd-Even • Cronbach’s Coefficient Alpha • Kuder-Richardson**Split-half or Odd-even Reliability**• Correlate one half of test with other half for all who took the test • Example: • Person 1 scores 16 on first half of test and 16 on second half • Person 2 scores 14 on first half and 18 on second half • Also get scores for persons 3, 4, 5, etc. • Correlate all persons scores on first half with their scores on second half • The correlation = the reliability estimate • Use “Spearman Brown formula to control for shortness of test**A**Split-half or Odd-even Reliability Internal Consistency • Example Continued: • Person Score on 1st Half Score on 2nd half • 1 16 16 • 2 14 18 • 3 12 20 • 4 15 17 • And so forth….. • Problem: Are any two halves really equivalent? • Graphic:**A**Cronbach’s Alpha and Kuder-Richardson Internal Consistency • Other types of Internal Consistency: • Average correlation of all of the possible split-half reliabilities • Two popular types: • Cronbach’s Alpha • Kuder-Richardson (KR-20, KR-21) • Graphic:**Cross-Cultural Fairness**• Issues of bias in testing did not get much attention until civil rights movement of 1960’s. • Series of court decisions established is was unfair to use tests to track students in schools. • Black and Hispanic students were being unfairly compared to whites-not their norm group.**Cross-Cultural Fairness**• Americans with Disabilities Act: • Accommodations for individuals taking tests for employment must be made • Tests must be shown to be relevant to the job in question. • Buckley Amendment (FERPA): • Right to access school records, including test records. • Parents have the rights to their child’s records**Cross-Cultural Fairness**• Carl Perkins Act: • Individuals with a disability have the right to vocational assessment, counseling and placement. • Civil Rights Acts: • Series of laws concerned with tests used in employment and promotion. • Freedom of Information Act: • Assures access to federal records, including test records. • Most states have expanded this law so that it also applies to state records.**Cross-Cultural Fairness**• Griggs v. Duke Power Company • Tests for hiring and advancement much show ability to predict job performance. • Example: Can’t give a test to measure intelligence for those who want to get a job as a road worker. • IDEIA and PL 94-142: • Assures rights of students (age 2 – 21) suspected of having a learning disability to be tested at the school’s expense. • Child Study Teams and IEP set up when necessary**Cross-Cultural Fairness**• Section 504 of the Rehabilitation Act: • Relative to assessment, any instrument used to measure appropriateness for a program or service must measure the individual’s ability, not be a reflection of his or he disability. • The Use of Intelligence Tests with Minorities: Confusion and Bedlam • (See Insert 3.1, p. 58)**Disparities in Ability**• Cognitive differences between people exist, however, they are clouded over by issues of SES, prejudice, stereotyping, etc: are there real differences? • Why do differences exist and what can be done to eliminate these differences? • Often seen as environmental-No Child Left Behind • Exercise 3.4, p. 58: Why might their be differences among cultural groups on their ability scores?**Practicality**• Several practical concerns: • Time • Cost • Format(clarity of print, print size, sequencing of questions and types of questions) • Readability • Ease of Administration, Scoring, and Interpretation**Selecting & Administering Tests**• Five Steps: • Determine your client’s goals • Choose instruments to reach client goals. • Access information about possible instruments: • Source books: E.g.,: Buros Mental Measurement Yearbook and Tests in Print • Publisher resource catalogs • Journals in the field • Books on testing • Experts • The internet • Examine validity, reliability, cross-cultural fairness, and practicality. • Make a wise choice.

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