Final answer:
A positive TB screening test is determined by the presence of a hard, raised red area on the skin test and requires further evaluation like chest radiographs to confirm due to potential false positives and errors in screening.
Step-by-step explanation:
A tuberculosis (TB) screening test reading that would be considered positive and require further evaluation typically has certain characteristics. If the screening, such as the Mantoux tuberculin skin test, shows a raised red area that is hard to the touch, called an induration, it indicates a positive test.
This suggests that the patient has been exposed to Mycobacterium tuberculosis and has a cellular immune response. However, it is important to recognize that a positive test could be a false positive, especially if the individual has been vaccinated with the BCG vaccine.
Therefore, a chest radiograph is necessary to confirm TB exposure due to the potential for both Type I and Type II errors in the screening test.
Type I error in the context of a TB screening test has an α level of 0.10, meaning there is a 10 percent chance of incorrectly detecting TB when it is not present. Conversely, a Type II error, with a β level of 0.20, means that there is a 20 percent chance of not detecting TB when it is indeed present. Nonetheless, the screening test is capable of detecting TB 80 percent of the time when it is present.