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# Test validity

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### Test validity

1. 1. Item Analysis, Test Validity and Reliability Prepared by: Rovel A. Aparicio Mathematics Teacher
2. 2. THERE IS always A better WAY
3. 3. Stages in Test Construction I. Planning the Test A. Determining the Objectives B. Preparing the Table of Specifications C. Selecting the Appropriate Item Format D. Writing the Test items E. Editing the Test items
4. 4. Stages in Test Construction II. Trying Out the Test A. Administering the test Item analysis C. Preparing the Final Form of the Test
5. 5. Stages in Test Construction III. Establishing Test Validity IV. Establishing Test Reliability V. Interpreting the Test Scores
6. 6. Item Analysis GOAL: Improve the test. IMPORTANCE: Measure the effectiveness of individual test item. DIFFICULTY INDEX DISCRIMINATION INDEX  the percentage  refers to the degree of the pupils who got the items rigth. interpreted as how easy or how difficult an item is. to which success or failure of an item indicates possession of the acheivement being measured.
7. 7. ACTIVITY NO.1 COMPUTE THE DIFFICULTY INDEX AND DISCRIMINATION INDEX OF PERIODICAL TEST.
8. 8. U-L INDEX METHOD (STEPS) 1. Score the papers and rank them from highest to lowest according to the total score. 2. Separate the top 27% and the bottom 27% of the papers. 3. Tally the responses made to each test item by each individual in the upper 27% group. 4.Tally the responses made to each test item by each individual in the lower 27% group.
9. 9. U-L INDEX METHOD (STEPS) 5. Compute the difficulty index. [d= (U+L)/(nu+nl)] 6. Compute the discrimination index. [D=(U-L)/nu] or [D=(U-L)/nl]
10. 10. Item no. Upper 27% 1 Lower 27% Difficulty Index 14 12 0.81 0.13 Revised 2 10 6 0.50 0.25 3 11 7 0.56 0.25 Retained Retained 4 9 2 0.34 0.44 Retained 5 12 0.56 0.38 Retained 6 6 6 14 0.63 -0.50 Rejected 7 13 4 0.53 0.56 Retained 8 3 10 0.41 -0.44 Rejected 9 13 12 0.78 0.06 Rejected 10 8 6 0.44 0.13 Revised No. of pupils tested- 60 Discrimination Index Remarks
11. 11. Item Analysis DIFFICULTY INDEX .00-.20 Very Difficult .21-.80 Moderately Difficult .81-1.00 DISCRIMINATION INDEX < .09 Poor items (Reject) .10-.39 Reasonably Good (Revise) .40-1.00 Very Good items (Retain) Very Easy
12. 12. Establishing Test Validity Criterionrelated Validity Content Validity Types of Test Validity Construct Validity
13. 13. Establishing Test Validity Types of Validity Types of Validity 1.Content Validity Meaning Meaning Procedure Procedure Compare test tasks How well the with test sample test bar specifications tasks represent describing the task the domain of domain under tasks to be consideration measured. (non-statistical)
14. 14. Establishing Test Validity Types of Validity Types of Validity 2. Construct Validity Meaning Meaning Procedure Procedure Experimentally determine what factors How test influence scores on test. performance can The procedure may be be described psychologically. logical and statistical using correlations and other statistical methods.
15. 15. Establishing Test Validity Types of Validity Types of Validity 3. Meaning Meaning Procedure Procedure Compare test scores How well test with measure of performance performance(grade) obtain on later date(for Criterion- predicts future performance prediction).or another related or estimates current measure of performance Validity performance on obtain concurrently(for some valued estimating present measures other status.( Primarily than the test Statistical). Correlate itself. test results with outside criterion.
16. 16. Establishing Test Reliability Measure of Stability and Equivalence Measure of Stability Types of Reliability Measure Measure of Internal Consistency Measure of Equivalence
17. 17. Establishing Test Reliability Types of Reliability Types of Reliability Measures Measures 1. Measure of Stability Methods of Methods of Estimating Reliability Estimating Reliability Test- retest method Procedure Procedure Give a test twice to the same group with any time interval between tests from several minutes to several years. (Pearson r)
18. 18. Establishing Test Reliability Types of Reliability Types of Reliability Measures Measures 2. Measure of Equivalence Methods of Methods of Estimating Reliability Estimating Reliability Procedure Procedure Give two forms of a Equivalent formstest to the same group in close method succession (Pearson r)
19. 19. Establishing Test Reliability Types of Reliability Types of Reliability Measures Measures 3. Measure of Stability Methods of Methods of Estimating Reliability Estimating Reliability Procedure Procedure Give two forms of a test to the same Test- retest with equivalentgroup with increased time intervals forms between forms. (Pearson r)
20. 20. Establishing Test Reliability Types of Reliability Types of Reliability Measures Measures 4. Measure of internal consistency Methods of Methods of Estimating Reliability Estimating Reliability Procedure Procedure Give a test once. Kuder-Richarson Score the total test method and apply the Kuder Richardson formula.
21. 21. Establishing Test Reliability Types of Reliability Types of Reliability Measures Measures 4. Measure of internal consistency Methods of Methods of Estimating Reliability Estimating Reliability Split half method Procedure Procedure Give a test once. Score equivalent halves of the test. (e.g. odd and even numbered items. (Pearson r and Spearman- Brown formula)
22. 22. ACTIVITY NO.2 TEST THE RELIABILITY OF PERIODICAL TEST.
23. 23. Pearson r Standard Scores (Directions) 1. Begin by writing the pairs of scores to be studied in two columns. Be sure that the pair of scores for each pupils is in the same row. Label one set of scores X , the other Y. 2.Get the sum (∑) of the scores for each column. Divide the sum by the number of scores (N) in each column to get the mean. 3.Subtract each score in column X from the mean x. Write the difference in column x. Be sure to put an algebraic sign.
24. 24. Pearson r Standard Scores (Directions) 4. Subtract each score in column Y from the mean y. Write the difference in column y. Don't forget the sign. 5. Square each score in column X. Enter each result under X2 . 6. Square each score in column Y. Enter each result under Y2 . 7. Compute the standard deviation of X and Y and enter the result under the column of SDx and SDy respectively .
25. 25. Pearson r Standard Scores (Directions) 8. Divide each entry in column x and y by the standard deviation SDx and SDy respectively and enter the result under Zx and Zy respectively. 9. Multiply Zx and Zy and enter the result under ZxZy. 10. Get the sum (∑) ZxZy. 11. Apply the formula r=∑ZxZy N
26. 26. Interpretation of Coefficient of Correlation Correlation is a measure of relationship between two variables. Magnitude or size of Relationship 0.8 and above means high correlation 0.5 means moderate correlation 0.3 and below means low correlation Direction of Relationship Negative coefficient means, as one variable increases, the other decreases. Positive Coefficient means, as one variable increases, the other also increases
27. 27. Interpretation of Coefficient of Variation Coeffecient of Variation is defined as the ratio of the standard deviation and the mean and usually expressed in percent. Criteria: c.v. = (mean/s.d.)x100 less than 10%Homogenous greater than 10%- Heterogenous
28. 28. REMEMBER: 1. Use item analysis procedures to check the quality of the test. The item analysis should be interpreted with care and caution 2. A test is valid when it measures what it is supposed to measure 3. A test is reliable when it is consistent .