Our new explainer looks at the key things Americans should know about election polling this year: www.pewresearch.org/short-reads/... One key point: While polling methods have diversified greatly in recent years, not all methods are equally sound. Caveat emptor.

Another key point: The real margin of error in surveys is often about double the one reported. "Sampling error is not the only kind of error that affects a poll. Those other kinds of error, in fact, can be as large or larger than sampling error." www.pewresearch.org/short-reads/...