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# Ch05 instrumentation

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### Ch05 instrumentation

1. 1. Educational Research Chapter 5 Selecting Measuring Instruments Gay, Mills, and Airasian
2. 2. Topics Discussed in this Chapter  Data collection  Measuring instruments  Terminology  Interpreting data  Types of instruments  Technical issues  Validity  Reliability  Selection of a test
3. 3. Data Collection  Scientific inquiry requires the collection, analysis, and interpretation of data  Data – the pieces of information that are collected to examine the research topic  Issues related to the collection of this information are the focus of this chapter
4. 4. Data Collection  Terminology related to data  Constructs – abstractions that cannot be observed directly but are helpful when trying to explain behavior  Intelligence  Teacher effectiveness  Self concept Obj. 1.1 & 1.2
5. 5. Data Collection  Data terminology (continued)  Operational definition – the ways by which constructs are observed and measured  Weschler IQ test  Virgilio Teacher Effectiveness Inventory  Tennessee Self-Concept Scale  Variable – a construct that has been operationalized and has two or more values Obj. 1.1 & 1.2
6. 6. Data Collection  Measurement scales  Nominal – categories  Gender, ethnicity, etc.  Ordinal – ordered categories  Rank in class, order of finish, etc.  Interval – equal intervals  Test scores, attitude scores, etc.  Ratio – absolute zero  Time, height, weight, etc. Obj. 2.1
7. 7. Data Collection  Types of variables  Categorical or quantitative  Categorical variables reflect nominal scales and measure the presence of different qualities (e.g., gender, ethnicity, etc.)  Quantitative variables reflect ordinal, interval, or ratio scales and measure different quantities of a variable (e.g., test scores, self-esteem scores, etc.) Obj. 2.2
8. 8. Data Collection  Types of variables  Independent or dependent  Independent variables are purported causes  Dependent variables are purported effects  Two instructional strategies, co-operative groups and traditional lectures, were used during a three week social studies unit. Students’ exam scores were analyzed for differences between the groups.  The independent variable is the instructional approach (of which there are two levels)  The dependent variable is the students’ achievement Obj. 2.3
9. 9. Measurement Instruments  Important terms  Instrument – a tool used to collect data  Test – a formal, systematic procedure for gathering information  Assessment – the general process of collecting, synthesizing, and interpreting information  Measurement – the process of quantifying or scoring a subject’s performance Obj. 3.1 & 3.2
10. 10. Measurement Instruments  Important terms (continued)  Cognitive tests – examining subjects’ thoughts and thought processes  Affective tests – examining subjects’ feelings, interests, attitudes, beliefs, etc.  Standardized tests – tests that are administered, scored, and interpreted in a consistent manner Obj. 3.1
11. 11. Measurement Instruments  Important terms (continued)  Selected response item format – respondents select answers from a set of alternatives  Multiple choice  True-false  Matching  Supply response item format – respondents construct answers  Short answer  Completion  Essay Obj. 3.3 & 11.3
12. 12. Measurement Instruments  Important terms (continued)  Individual tests – tests administered on an individual basis  Group tests – tests administered to a group of subjects at the same time  Performance assessments – assessments that focus on processes or products that have been created Obj. 3.6
13. 13. Measurement Instruments  Interpreting data  Raw scores – the actual score made on a test  Standard scores – statistical transformations of raw scores  Percentiles (0.00 – 99.9)  Stanines (1 – 9)  Normal Curve Equivalents (0.00 – 99.99) Obj. 3.4
14. 14. Measurement Instruments  Interpreting data (continued)  Norm-referenced – scores are interpreted relative to the scores of others taking the test  Criterion-referenced – scores are interpreted relative to a predetermined level of performance  Self-referenced – scores are interpreted relative to changes over time Obj. 3.5
15. 15. Measurement Instruments  Types of instruments  Cognitive – measuring intellectual processes such as thinking, memorizing, problem solving, analyzing, or reasoning  Achievement – measuring what students already know  Aptitude – measuring general mental ability, usually for predicting future performance Obj. 4.1 & 4.2
16. 16. Measurement Instruments  Types of instruments (continued)  Affective – assessing individuals’ feelings, values, attitudes, beliefs, etc.  Typical affective characteristics of interest  Values – deeply held beliefs about ideas, persons, or objects  Attitudes – dispositions that are favorable or unfavorable toward things  Interests – inclinations to seek out or participate in particular activities, objects, ideas, etc.  Personality – characteristics that represent a person’s typical behaviors Obj. 4.1 & 4.5
17. 17. Measurement Instruments  Types of instruments (continued)  Affective (continued)  Scales used for responding to items on affective tests  Likert  Positive or negative statements to which subjects respond on scales such as strongly disagree, disagree, neutral, agree, or strongly agree  Semantic differential  Bipolar adjectives (i.e., two opposite adjectives) with a scale between each adjective  Dislike: ___ ___ ___ ___ ___ :Like  Rating scales – rankings based on how a subject would rate the trait of interest Obj. 5.1
18. 18. Measurement Instruments  Types of instruments (continued)  Affective (continued)  Scales used for responding to items on affective tests (continued)  Thurstone – statements related to the trait of interest to which subjects agree or disagree  Guttman – statements representing a uni- dimensional trait Obj. 5.1
19. 19. Measurement Instruments  Issues for cognitive, aptitude, or affective tests  Problems inherent in the use of self-report measures  Bias – distortions of a respondent’s performance or responses based on ethnicity, race, gender, language, etc.  Responses to affective test items  Socially acceptable responses  Accuracy of responses  Response sets  Alternatives include the use of projective tests Obj. 4.3, 4.4
20. 20. Technical Issues  Two concerns  Validity  Reliability
21. 21. Technical Issues  Validity – extent to which interpretations made from a test score are appropriate  Characteristics  The most important technical characteristic  Situation specific  Does not refer to the instrument but to the interpretations of scores on the instrument  Best thought of in terms of degree Obj. 6.1 & 7.1
22. 22. Technical Issues  Validity (continued)  Four types  Content – to what extent does the test measure what it is supposed to measure  Item validity  Sampling validity  Determined by expert judgment Obj. 7.1 & 7.2
23. 23. Technical Issues  Validity (continued)  Criterion-related  Predictive – to what extent does the test predict a future performance  Concurrent - to what extent does the test predict a performance measured at the same time  Estimated by correlations between two tests  Construct – the extent to which a test measures the construct it represents  Underlying difficulty defining constructs  Estimated in many ways Obj. 7.1, 7.3, & 7.4
24. 24. Technical Issues  Validity (continued)  Consequential – to what extent are the consequences that occur from the test harmful  Estimated by empirical and expert judgment  Factors affecting validity  Unclear test directions  Confusing and ambiguous test items  Vocabulary that is too difficult for test takers Obj. 7.1, 7.5, & 7.7
25. 25. Technical Issues  Factors affecting validity (continued)  Overly difficult and complex sentence structure  Inconsistent and subjective scoring  Untaught items  Failure to follow standardized administration procedures  Cheating by the participants or someone teaching to the test items Obj. 7.7
26. 26. Technical Issues  Reliability – the degree to which a test consistently measures whatever it is measuring  Characteristics  Expressed as a coefficient ranging from 0 to 1  A necessary but not sufficient characteristic of a test Obj. 6.1, 8.1, & 8.7
27. 27. Technical Issues  Reliability (continued)  Six reliability coefficients  Stability – consistency over time with the same instrument  Test – retest  Estimated by a correlation between the two administrations of the same test  Equivalence – consistency with two parallel tests administered at the same time  Parallel forms  Estimated by a correlation between the parallel tests Obj. 8.1, 8.2, 8.3, & 8.7
28. 28. Technical Issues  Reliability (continued)  Six reliability coefficients (continued)  Equivalence and stability – consistency over time with parallel forms of the test  Combines attributes of stability and equivalence  Estimated by a correlation between the parallel forms  Internal consistency – artificially splitting the test into halves  Several coefficients – split halves, KR 20, KR 21, Cronbach alpha  All coefficients provide estimates ranging from 0 to 1 Obj. 8.1, 8.4, 8.5, & 8.7
29. 29. Technical Issues  Reliability (continued)  Six reliability coefficients  Scorer/rater – consistency of observations between raters  Inter-judge – two observers  Intra-judge – one judge over two occasions  Estimated by percent agreement between observations Obj. 8.1, 8.6, & 8.7
30. 30. Technical Issues  Reliability (continued)  Six reliability coefficients (continued)  Standard error of measurement (SEM) – an estimate of how much difference there is between a person’s obtained score and his or her true score  Function of the variation of the test and the reliability coefficient (e.g., KR 20, Cronbach alpha, etc.)  Estimated by specifying an interval rather than a point estimate of a person’s score Obj. 8.1, 8.7, & 9.1
31. 31. Selection of a Test  Sources of test information  Mental Measurement Yearbooks (MMY)  The reviews in MMY are most easily accessed through your university library and the services to which they subscribe (e.g., EBSCO)  Provides factual information on all known tests  Provides objective test reviews  Comprehensive bibliography for specific tests  Indices: titles, acronyms, subject, publishers, developers  Buros Institute Obj. 10.1 & 12.1
32. 32. Selection of a Test  Sources (continued)  Tests in Print  Tests in Print is a subsidiary of the Buros Institute  The reviews in it are most easily accessed through your university library and the services to which they subscribe (e.g., EBSCO)  Bibliography of all known commercially produced tests currently available  Very useful to determine availability  Tests in Print Obj. 10.1 & 12.1
33. 33. Selection of a Test  Sources (continued)  ETS Test Collection  Published and unpublished tests  Includes test title, author, publication date, target population, publisher, and description of purpose  Annotated bibliographies on achievement, aptitude, attitude and interests, personality, sensory motor, special populations, vocational/occupational, and miscellaneous  ETS Test Collection Obj. 10.1 &12.1
34. 34. Selection of a Test  Sources (continued)  Professional journals  Test publishers and distributors  Issues to consider when selecting tests  Psychometric properties  Validity  Reliability  Length of test  Scoring and score interpretation Obj. 10.1, 11.1, & 12.1
35. 35. Selection of a Test  Issues to consider when selecting tests  Non-psychometric issues  Cost  Administrative time  Objections to content by parents or others  Duplication of testing Obj. 11.1
36. 36. Selection of a Test  Designing your own tests  Get help from others with experience in developing tests  Item writing guidelines  Avoid ambiguous and confusing wording and sentence structure  Use appropriate vocabulary  Write items that have only one correct answer  Give information about the nature of the desired answer  Do not provide clues to the correct answer  See Writing Multiple Choice Items Obj. 11.2
37. 37. Selection of a Test  Test administration guidelines  Plan ahead  Be certain that there is consistency across testing sessions  Be familiar with any and all procedures necessary to administer a test Obj. 11.4