Collocations for observer - noun

casual
To the casual observer, it would have looked like any other domestic argument.

informed, knowledgeable (esp. AmE)
acute, astute, careful, close, keen, shrewd
experienced, long-time, seasoned
sceptical/skeptical
sympathetic
detached, impartial, neutral, objective, unbiased
reasonable
external, independent, outside
Independent observers will monitor the elections.

trained
foreign, international
American, Western, etc.
industry, legal, media, military, political
Some military observers fear the US could get entangled in another war.

election
human
passive

send
Observers were sent to check the conduct of the elections.

attend sth as
impress, puzzle, shock, strike, stun, surprise
The suddenness of this move surprised observers.

see sth
note sth, say sth
agree sth
believe sth, think sth
expect sth, predict sth
attend sth
The talks were attended by observers from eight Arab countries and Israel.

monitor sth

status
The country was granted observer status at the summit.

bias

as an observer
I attended the conference as an observer.

observer of
an observer of the American cultural scene

lead observers to conclude, suggest, etc. sth
Difficulties in the housing market have led some observers to conclude that house prices will fall dramatically.