Suppose the investigators plan a larger study comparing the two tests. How many infants need to be tested to have an 80% probability of finding a significant difference using a two-sided test with α = 0.05 if the proportion of test results in the four groups in Table 10.44 are considered to be the true proportions? 

A new test is proposed that may be better or worse than the standard test. To assess their relative efficacy, a pilot study is conducted where both tests are used on the same subjects and compared with the true diagnosis. Let + = correct assessment, ˆ’ = incorrect assessment. The results are given in Table 10.44.

Table 10.44: Comparison of two screening tests for Down€™s syndrome

 

Thus, for 82 infants, both tests make the correct classification, for 3 infants both tests make the wrong classification, for 5 infants the standard test makes the correct diagnosis while the new test does not, and for 10 infants the new test makes the correct diagnosis while the standard test does not. 

Transcribed Image Text:

Standard test New test 82 5 10 3 100