Refer ace to the definition of a psychological test with this discussion opened will show that such a test was characterized as an objective as well as a standardized measure.
Some aspects of objectivity of psychological tests have already been described in the discussion of standardization thus the administration, scoring, and interpretation of scores are objective insofar as they are independent of the subjective judgment of the particular examiner.
- Any test taker should theoretically obtain identical scores on a test regardless of who happens to be the examiner. This is not entirely so, of course, because perfect standardization and objectivity have not been attained in practice but at least such objectivity is the goal of test construction and has been achieved to a reasonably high degree in most tests.
- The determination of the difficulty level of an item or of a whole test is based on objective empirical procedures.
- Binet and Simon prepared their original, 1905 scale for the measurement of intelligence. They arranged 30 items of the scale in order of increasing difficulty. Such difficulty was determined by trying out the items on 50 normal and a few mentally related children.
There are no arrangements but also the selection of items for inclusion in a test can be guided by the proportion of persons in the trial samples who pass the item. Thus, if there is a bunching of items at the easy or difficult end of the scale, some items will be discarded. Similarly, if items are spare in a certain portion of the difficulty range, new items can be added to fill the gap.