A group of researchers is investigating a new serological assay for a tick-borne illness. They recruit subjects from an endemic region. All subjects undergo both the new serological assay and the gold-standard polymerase chain reaction (PCR) test.
The PCR test confirms that subjects have the illness.
Among these infected subjects, have a positive result on the new serological assay.
Among the subjects who test negative for the illness by PCR, test negative on the new serological assay, while test positive.
A -year-old man from this region undergoes the new serological assay, and the result is positive. Based on the study results, what is the percentage probability that this man actually has the tick-borne illness?
Cevap: 50 %
Cevap
50
The question asks for the probability that a patient with a positive test actually has the disease, given the population parameters provided. This requires calculating the ratio of true positives to total positives. The true positives are the 90 infected subjects who tested positive. The total positive tests include these 90 true positives plus the 90 uninfected subjects who falsely tested positive (90 + 90 = 180). Therefore, the probability is 90 / 180 = 0.50, or 50%.
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The probability that a patient with a positive test result actually has the disease is determined by calculating the True Positives divided by the Total Positives (True Positives + False Positives).