Overestimation error is a measure of the difference between a diagnostician's certainty in a diagnosis and what it should be based on available evidence.


overestimation error =

= (percent given by diagnostician as the probability of a diagnosis) - (percent probability based on available evidence)



• The ratio of the 2 values might also provide a measure of deviation.

• Ratio = (percent certainty given by the diagnostician) / (percent certainty based on available data)



• A value near 0 indicates a current estimate of diagnostic probability.

• A large value indicates overestimation (overdiagnosis).

• A negative value indicates underestimation (underdiagnosis).


Consequences of overdiagnosis:

(1) unnecessary therapy

(2) unnecessary diagnostic tests


Reasons for overdiagnosis:

(1) placing more importance on a finding than justified

(2) failure to consider all evidence

(3) placing more emphasis on the consequences of failing to make the diagnose


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