Conditions that are less than ideal are pervasive throughout society, and are seldom acted upon by government until they are perceived as a problem. A focusing event is often some type of natural catastrophe such as a hurricane or devastating flood. A decline in the stock market or an increase in the number of birth defects are examples of the types of indicators that, when of sufficient magnitude, can gain enormous attention from politicians, the press, and the public.
Officials also learn about problems through formal and informal feedback.
A report derived from the routine monitoring of costs for a government program would constitute a form of formal feedback. Not all problems can be solved by government intervention, and some matters simply fade away because attention wanes, or other more pressing issues emerge. Some problems are of a cyclical nature and correct themselves over time. Problems rarely constitute an agenda item in and of themselves. The policy stream is dependent on a group of hidden participants consisting primarily of specialists in government, academics, and special interest groups.