Adapted from Assessment in Special and incl.docx
- 1. Adapted from: Assessment in Special and inclusive education Salvia, Ysseldyke, Bolt. Module 2 Technical Prerequisites for Understanding Assessments Prerequisites for Understanding Assessments Descriptive Statistics: A description of what generated data shows. Descriptive statistics aim to summarize basic quantitative concepts. Descriptive statistics include the following:
- 2. 1. Scales of measurement: Ordinal scale: allows for rank order (1st, 2nd, 3rd, etc.) by which data can be sorted, but does not allow for relative degree of difference between them. Equal interval scale: also rank orders things, however, the magnitude of difference between values is known (i.e., measurement of time, length, weight, etc.) Prerequisites for Understanding Assessments Sets of equal-interval scores( student scores on a classroom test) can be described in terms of four characteristics: (1) Mean –Arithmetic average (2) Variance – dispersion of a set of scores around the mean of distribution (3) Skew – asymmetry in a distribution (the distribution does not follow the NCE) Note the samples in the following frames: Prerequisites for Understanding Assessments
- 3. A distribution is skewed if one of its tails is longer than the other. The first distribution shown has a positive skew. This means that it has a long tail in the positive direction. Prerequisites for Understanding Assessments The distribution below it has a negative skew since it has a long tail in the negative direction. the third distribution is symmetric and has no skew. Prerequisites for Understanding Assessments (4) Kurtosis: how high a curve rises, the peakedness of a curve.
- 4. Prerequisites for Understanding Assessments Validity Validity: the degree to which a test measures what it is supposed to measure. There are three basic approaches to the validity of tests and measures as shown by Mason and Bramble (1989). These are content validity, construct validity, and criterion-related validity. Content Validity: This approach measures the degree to which the test items represent the domain or universe of the trait or property being measured. In order to establish the content validity of a measuring instrument, the educator must identify the overall content to be represented. Prerequisites for Understanding Assessments Construct Validity: the extent to which a test measures a theoretical trait or characteristic. Criterion related validity: extent to which a person’s score on a criterion measure can be estimated from that persons score on a test of unknown validity.
- 5. Prerequisites for Understanding Assessments Reliability Reliability: concerns the extent to which the instrument yields the same results on repeated trials. Retest Method : the same test is given to the same people after a period of time. The reliability of the test (instrument) can be estimated by examining the consistency of the responses between the two tests. Alternative Form Method: this method also requires two testing's with the same people. However, the same test is not given. Each of the two tests must be designed to measure the same thing and should not differ in any systematic way. One way to help ensure this is to use random procedures to select items for the different tests. Prerequisites for Understanding Assessments Split-Halves Method: This method is more practical in that it does not require two administrations of the same or an alternative form test. In the split-halves method, the total number of items is divided into halves, and a correlation taken between the two halves.
- 6. Test Reliability is an important selling point for publishers of standardized tests, especially in high-stakes testing. If an institute asserts that its instrument can identify children who qualify for a special education program, the users of that test would hope that it has a high reliability. Otherwise, some children requiring the special education may not be identified, whereas others who do not require the special education may be unnecessarily assigned to the special education program. Prerequisites for Understanding Assessments Minimum Standards for Reliability: Test scores used for administrative purposes and reported for groups of students; a reliability of .60 should be the minimum. This low standard is acceptable because group means are not affected by a tests lack of reliability For weekly (or more frequent) testing used to monitor student progress, a reliability of .70 should be the minimum. This relativity low standard is acceptable because random fluctuations can be taken into account when a behavior or skill is measured often. If a decision is being made is a screening decision (i.e., used as a recommendation for further assessment) there needs to be higher reliability. For screening purposes a standard of .80 is recommended If a test is used to make decisions for an individual student (tracking, or special educational placement) the recommended standard is .90
- 7. Prerequisites for Understanding Assessments Measures of Dispersion: Range: The difference between extremes of a distribution Variance: description of the dispersion ofa set of scores around the mean. Standard Deviation: the positive square root of the variance. Prerequisites for Understanding Assessments Standard Error of Measurement Prerequisites for Understanding Assessments Prerequisites for Understanding Assessments Summarizing Student Performance
- 8. 1. Percent correct 2. Accuracy 3. Instructional level Frustration: (too difficult- the stduetn knows less than 85% of the material Instructional: material where the child is likely to be successful , but success is not guaranteed (responses between 85-95% correct) Independent: the student can perform without assistance more than 95% accuracy) Prerequisites for Understanding Assessments Interpretation of Test Performance There are 3 common ways to interpret an individual students performance: 1. criterion referenced: given by teachers to establish how well students have learned the data and skills that were taught in the class. Standards referenced (Standards Based Assessment, content standards or curriculum frameworks), adopted by states and districts that describe what students should know and be able to do in different subjects at various grade levels. They also have performance standards that define how much of the content standards students should know to reach the "basic" or "proficient" or "advanced" level in the subject area.
- 9. Prerequisites for Understanding Assessments Norm referenced: a type of test, assessment, or evaluation which yields an estimate of the position of the tested individual in a predefined population, with respect to the trait being measured. Important Characteristics for Normed Assessments: 1. Gender 4. Race and Cultural Identity 2. Age 5. Geography 3. Grade on School 6. Intelligence 7. Acculturation of parents