straw poll 
(North American also straw vote)
noun
An unofficial ballot conducted as a test of opinion: I took a straw poll among my immediate colleagues...
- When compiling the form statisticians wanted to ask people how much they earned - but, having conducted a straw poll which indicated this would not be welcomed by the public, the idea was dropped.
- Holmes said that at the last meeting of the association at Headingley he conducted a straw poll to see what members felt about Gough and the overwhelming majority wanted him to stay with Yorkshire.
- With this in mind, I conducted a quick straw poll.