Imagine that you have examined 100 patients that are similar to this one. You have order ultrasounds for all of these patients. Since the ultrasound is considered your “gold standard”, we will assume that all ultrasound results are correct (without autopsies!).

Of the 100 ultrasounds that are returned to you, 40 patients are classified as having an enlarged thyroid by ultrasound. 60 patients are classified as not having a thyroid enlargement by ultrasound. These are your “gold standard” assessment.

You start to construct a 2x2 table to summarize your findings.