A Study of Hypotheses Basic to the Use of Rights and Formula Scores

The hypothesis that some students, when tested under formula directions, omit items about which they have useful partial knowledge implies that such directions are not as fair as rights directions, especially to those students who are less inclined to guess. This hypothesis may be called the differential effects hypothesis. An alternative hypothesis states that examinees would perform no better than chance expectation on items that they would omit under formula directions but would answer under rights directions. This may be called the invariance hypothesis. Experimental data on this question were obtained by conducting special test administrations of College Board SAT‐verbal and Chemistry tests and by including experimental tests in a Graduate Management Admission Test administration. The data provide a basis for evaluating the two hypotheses and for assessing the effects of directions on the reliability and parallelism of scores for sophisticated examinees taking professionally developed tests. Results support the invariance hypothesis rather than the differential effects hypothesis.