That widely quoted "probability of a hike" is not a forecast. It is a quote — as in a price.

The Fed meets July 28–29, its fifth gathering of the year, with the decision landing Wednesday afternoon in New York. For two weeks the previews have been unanimous: the side betting on a hike has gotten noticeably thicker, and quickly. So the percentage has been promoted to the wisdom of the crowd — as if every participant in the market held a meeting, took a vote, and handed you the tally.