This hypothetical example demonstrates the odds. If the test value is <1 then all the people tested are strongly positive. If it is between 1 and 3 then it is positive but less so. If the value is 4 – 6 then the odds are even and you cannot say if the result is found in a diseased or healthy person. As the values increase the odds of the test results being in a healthy person increase. In this example if a patient had a value for the test of 0.5 last week, but a value of 2.5 today then the patient is probably getting better. But if the value were 4.5 the you’re more sure of improvement (but you still could be wrong).