What is observer expectancy?

Participant and Player.

the place where someone is standing on the earth, defined by his meridian of longitude

The difference between life expectancy and healthy life expectancy is that life expectancy is referred to the life expectancy if existing mortality patterns continue calculated at birth,unless...

Life expectancy is the average number of years of life remaining at a given age

During World War 2 in England, the observer corps would observe enemy aircraft and call in their speed, direction, and height to a central location. That would alert the Royal Air Force where to send...