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Standards of Quality of a Aptitude and Psychometric Test
The considerations of validity and reliability are viewed as essential elements for determining the quality of a Psychometric test. However, professional and practitioner associations frequently have placed these concerns within broader contexts when developing standards and making overall judgments about the quality of any test as a whole within a given context. A consideration of concern in many applied research settings is whether or not the metric of a given psychological inventory is meaningful.
Validity of the test concerns what the test measures and how well it does so. It tells what can be inferred from the test scores. In this connection, one should guard against accepting the test name as an index of what the test measures. Test names provide short, convenient labels for identification purposes. The validity of a test cannot be reported in general terms. No test can be said to have “HIGH” or “LOW” validity in the abstract. Its validity must be established with reference to the particular use for which the test is being considered.
For establishing the validity of any psychological test, following aspects will be taken into consideration:
1. Face Validity
a. Content Validity
b. Observation Validity
i. Concurrent Validity
ii. Predictive Validity
c. Convergent Validity
d. Discrimination Validity
2. Internal Validity
3. External Validity
a. Ecological Validity
b. Population Validity
4. Construct Validity
Based on the above mentioned validity patterns Statistical Conclusions will be drawn to establish Validity norms
Reliability is the consistency of a set of measurements. Reliability is the extent to which the measurements of a test remain consistent over repeated tests of the same subject under identical conditions. An experiment is reliable if it yields consistent results of the same measure.
It is the consistency of the scores that an individual gets on a psychological test. This can be whether the measurements of the same instrument give (test-retest) is likely to give the same measurement, or in the case of more subjective instruments, whether two independent assessors give similar scores (inter-rater reliability). Reliability does not imply validity. That is, a reliable measure is measuring something consistently, but not necessarily what it is supposed to be measuring.
Reliability may be estimated through a variety of methods. To establish the Reliability of the test various the scores from the random sample drawn from the population are subjected to various statistics like Pearson Product-moment correlation coefficient, Spearman-Brown Prediction Formula. The most common internal consistency measure is Cronbach's alpha, which is usually interpreted as the mean of all possible split-half coefficients.
Norms: It is very important to understand how the scores obtained on a psychological test are interpreted. A raw score on any psychological test is meaning less without additional interpretive data. Scores on psychological tests are most commonly interpreted by reference to norms that represent the test performance of the standardization sample. The raw scores obtained in a test are converted into standard scores and norms are established by determining what persons in a representative group actually do on the test. Any individual’s raw score is then referred to the distribution of scores obtained by the standardization sample to discover where he or she falls in that distribution. Norms are developed with reference to culture, groups (Ingroup & Outgroup), Sex(Male & Female) etc.
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