Michelle Malkin provides an excellent example of bias category #4:
4. Polls. An offshoot of ventriloquist journalism is the MSM/DNC's reliance upon polls. The polls that the MSM/DNC uses are either (1) unreliable or blatantly false and/or (2) self-fulfilling prophecies. It is a common tendency among humans (especially those who have been softened by 70 years of the welfare state) to want to be on the winning side. When the MSM/DNC releases its polls showing some Democrat with a lead or that the "public" thinks that Social Security is just fine, those who might otherwise harbor doubts are intimidated into going along with the majority. I am sure that the MSM/DNC will continue their efforts to bully the public into acquiescing in the status quo on social security with just this tactic.
What I did not mention in the category post was the tendency of MSM/DNC polls to load their questions in such a way as to arrive at an MSM/DNC preferred result. This is the tactic used in the latest MSM/DNC poll on the judicial nominee filibuster issue.
Why would anyone skew a poll to achieve a desired result? That approach is hardly scientific. The only reason for purposely skewing poll results is that the result can be used to influence events. The poll becomes a self-fulfilling prophecy. Those who commissioned and report the poll favor the filibuster and use flawed polls to help achieve that result.