What is needed alongside true negatives to calculate specificity of a laboratory test?

To calculate the specificity of a laboratory test, it is essential to have the number of true negatives alongside the number of false positives. Specificity is a measure of a test's ability to correctly identify those without the disease, conveying how well the test performs in ruling out non-diseased individuals. The formula for specificity is:

Specificity = True Negatives / (True Negatives + False Positives)

In this formula, true negatives represent the individuals correctly identified as not having the condition, while false positives are those incorrectly identified as having the condition. Thus, the presence of false positives is crucial because they directly affect the calculation of specificity. The interplay between true negatives and false positives allows for a comprehensive assessment of a test's accuracy in avoiding false diagnoses.