What are the criteria and characteristics of good evaluation tools ?
Illustrate the factors/types to be considered to improve the validity/reliability of the test.
Introduction
Evaluation is quantitative as well as qualitative in nature and uses a wide variety of evaluation tools to achieve its purpose.
Criteria and characteristics of a good evaluation tools
Commonly accepted qualities of good evaluation tools –.
1. Validity –
The degree or extent to which a tool actually, accurately, efficiently and infallibly measures what it is supposed to measure. Validity may be of low, high or moderate degree.
2. Reliability –
The consistency or stability of scores obtained by the same individual under re-examination and variable examining conditions.
3. Objectivity –
Elimination of personal judgement and bias factor from the scoring.
4. Adequacy –
The extent of subject matter covered. A good test will be long enough and balanced enough to judge the objective widely. i.e. cover maximum syllabus.
5. Usability/Practicability –
Ease of administering, ease of interpretation, usage of scores, economical, etc.
6. Discriminating power –
It should be able to classify and differentiate between students based on their aptitude and achievement shown in the test.
Factors affecting validity
1. Unclear directions –
Students should know how to respond to the items. Eg. Write in one word, 3-4 sentences, match the columns, etc.
2. Reading Vocabulary and Sentence Construction –
Simple language will help students to understand the question clearly.
3. Medium of Expression –
Medium of answering should be in the language the students are most comfortable with so that their answers are judged based on the content and not on their grammar and vocabulary.
4. Difficulty level –
The test should not be very difficult or too easy.
5. Poorly constructed items –
Test items should not provide clues to the answer else it only measures alertness of the student and not his capability.
6. Use of inappropriate items –
Knowledge and comprehension and application based questions improve validity rather than factual information like dates of birth.
7. Inappropriate time limit –
The test should be appropriately timed and should not be a speed test.
8. Influence of extraneous factors –
Examiners should be free from the influence of handwriting, neatness, grammar, length of answer, etc.
9. Inadequate coverage –
Testing only a few topics out of the many told to study (say 5 out of 20), the test fails to measure its objective.
10. Halo effect –
Giving more marks to a teacher’s pet and less to the bully, lowers its validity.
11. Questions in the form of quiz –
The questions should be clear without any guess factor involved otherwise students are confused about what they should answer.
Factors affecting reliability
1. Length of test –
Lengthening a test will increase its reliability. Eg.
More reliable > > 50 items >> 20 items >> 2 items>> less reliable.
2. Objectivity –
Objective type tests are more reliable as long as they include valid items and do not contain elements of chance (such as True-False).
3. Range of talent –
Administering a test to a large group of heterogeneous talent and obtaining a variety of scores in the results, improves reliability of the test.
4. Difficulty level –
Too easy or too difficult tests reduce reliability as many students might score the same marks and then one cannot differentiate between their abilities.
5. Ambiguous wording of questions –
Questions should be clear with no ambiguity. The same questions should always be understood in the same manner by the same student at different points of time.
6. Testing Condition –
External factors such as emotions, illness, improper ventilation, etc can make the scores unstable and produce unreliability.
7. Use of optional questions –
If students attempt separate options then one cannot compare or judge their scores against one another or the entire group. So Reliability reduces.
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