ABSTRACT
The basic purpose of performance assessment and other forms of human measurement is to enable teachers to learn more about themselves. The performance of students on testing measures is a function of many variables, not the least of which is the quality of the measurement instrument itself. There are four essential components of a good measuring instrument for educational purposes—an objective scoring procedure, validity, reliability, and suitability. One way of describing a score is in terms of its relation to the average score for that group of measures. In statistics, there are three measures of central tendency or average: mode, median, and mean. The normal curve is a symmetrical distribution of measures. The degree of correlation between measures is usually the basis for inferring that the traits measured by the tests are also associated. Correlation is a useful tool in assessing the reliability and validity of tests.
