Characteristics of a Good Evaluation Tool

Most evaluations require the use of a data collection tool—a survey or other data collection instrument. Evaluators either need to adopt or adapt tools “off the shelf” or create new ones. Either method can pose challenges: Tools that have been developed for one evaluation may not prove suitable for another, at least not without careful modification. At the same time, creating new tools requires expertise in measurement and instrument design.

Desirable Characteristics of Evaluation Tools

The evaluation tools serve a variety of uses.  Regardless of the type of tool used or  how the results of evaluation are to be used, all types of evaluation should possess certain characteristics.  The most important characteristics are - validity, reliability and usability.

  1. Validity

Validity is the degree to which an evaluation tool actually serves the purpose for which it is intended.  It refers to the extent to which a test measures what it is supposed to measure.  Although there are several kinds of validity, the three types commonly used are criterion, content and construct.

 2.Reliability

Reliability refers to the consistency of measurement, that is, how consistent are evaluation results from one measurement to another.  Reliability is concerned with the extent to which an evaluation test is consistent in measuring what it is intended to measure.  Whether the response of the respond dents would have been different if they were tested yesterday or next week? How would the result have varied if a different sample of equivalent items had been selected? These are the types of questions with which reliability is concerned.  If the measurements are not consistent over different occasions or over different samples of the same performance domain, the evaluator can have little  confidence in the results.

3.  Usability

While selecting evaluation tool / instrument, practical considerations need to be kept in mind. Generally, the tests are administered by teachers having very limited training. The time available for testing is also limited. The cost of testing is also taken into consideration. All these factors must be taken into account when selecting evaluation tools.