Scoring: Measures of Central Tendency There are three measures: mean median mode

Mean Measurement of Scoring most used method Mean = average Mean = the sum of all scores divide by the # of scores affected by extreme scores Often use for: GPA ranking Field goal Average

Median Measurement of Scoring The middle score falls in the middle of the distribution; determines the 50th percentile the score that splits the distribution in half 50% of scores are above median 50% of scores are below the median

Mode Measurement of Scoring The score that occurs the most frequently. Called the modal score However you can sometimes get: No mode Bimodal - 2 scores that occur the same number of times multimodal

Lets Look at Some Examples Which scoring measurement is best to use?

Designing High-Quality Classroom Assessments What is the Criteria for Ensuring High-Quality Classroom Assessments?

High-Quality Assessments need: Clear and appropriate learning objectives Alignment Appropriateness of assessment method Validity Reliability Fairness

What is Assessment Validity ? Ask: Does the test measure what it is suppose to measure?

A Score is Generated- Validity Coefficient Validity Evidence Determine the soundness of your interpretations and uses of the students’ assessment results Uses statistical tools to test the results in order to determine the degree of confidence we can place on that test. A Score is Generated- Validity Coefficient

What is Assessment Reliability? Ask: Does the test yield the same or similar score rankings consistently?

Reliable Evidence Refers to the consistency with which it yields the same rank for individuals who take the test more than once Example : Step on a bathroom scale and take 5 weights over 1 hour. Measurements differ by 0.02 Is that scale Reliable?

What About These? 1st attempt 75 50 93 80 67 2nd Attempt 78 62 85 97 66

Problems with Reliability Students could have done better at guessing one time over the other Some memory of the first test How long of an interval between taking the tests? Too long vs. too short

Looking at Test Accuracy Does the test score closely approximate an individual’s true level of ability, skill, or aptitude?

Accuracy and Testing Error Tests make mistakes. All tests are associated with some degree of error. No Test measures perfectly

Error in Testing Error is any factor that leads an individual to perform better or worse on a test Therefore: it is not a true measurement of their level of performance.