[Profpat]

In what context David?

Metaphysically I guess it means what it says. In fact you could go further and say "the observer creates the observation. "

On a more real world basis I think there have been some studies now that confirm that we affect or influence the obervation.

On a physics level I agree with Greg.
That its relating to the uncetainty principle.
That you can't measure momentum and position simultaneously.

The very act of measuring changes, probability to actuality.

Best to all,

Pat