A trained observer can make a visual assessment based on factors like muscle wasting.

A trained observer selects the smallest target resolvable at each contrast level.

The significant wave height was intended to mathematically express the height estimated by a trained observer.

A trained observer estimated winds of over 150 mph (240 km/h), and winds in the territory were unofficially estimated as strong as 200 mph (325 km/h).

For once, the excuses of the highly paid performers and trained observers were valid.