True positive的意思

"True positive" is a term used in the field of statistics, particularly in the context of binary classification tasks, where an algorithm or system is used to predict a binary outcome (such as "disease present" or "disease absent"). The term is also used in diagnostic testing and machine learning.

A true positive (TP) occurs when:

• The test result is positive.
• The actual condition being tested for is present.

In other words, a true positive is a correct positive prediction. It indicates that the system correctly identified a case as positive when it actually was positive.

For example, in a medical context, a test for a particular disease might be said to have a true positive rate if it correctly identifies someone who has the disease as positive.

True positive is contrasted with other types of outcomes, such as:

• False positive (FP): A test result that is positive, but the actual condition being tested for is not present.
• True negative (TN): A test result that is negative, and the actual condition being tested for is not present.
• False negative (FN): A test result that is negative, but the actual condition being tested for is present.

The goal of any diagnostic or classification system is to maximize the true positives and true negatives while minimizing the false positives and false negatives. This is often expressed in terms of sensitivity (the ability of the test to correctly identify all positive cases) and specificity (the ability of the test to correctly identify all negative cases).