Margin of error explained
What does it mean when election polls refer to a margin of error?
Because polls cannot survey the entire population, pollsters use a sample. The sample size varies, but many polls use as few as a thousand people. The margin of error is calculated using the size of the whole population (the number of eligible voters) and the sample size of the poll.
In a poll where the margin of error is plus or minus 4 percent, 95 times out of 100 the percentage of people who would give the same answer in later polls would be within 4 percentage points of the original poll. If 57 percent of respondents say that they will vote for a candidate, for example, the number could range from 61 percent to 53 percent.
McCain's family tree
How old were John McCain's father and grandfather when they died, and what was the cause of death? What about siblings? Are they still living?
John McCain's father, Adm. John S. McCain Jr., was 70 when he died of a heart attack aboard a military aircraft in 1981. He was commander in chief of U.S. Pacific forces during the Vietnam War and a decorated World War II hero.
McCain's grandfather, Vice Adm. John Sidney McCain, commander of the Third Fleet Carrier Task Force, was 61 when he died at home of a heart attack, having recently returned from the World War II surrender ceremonies in Tokyo Bay.
McCain's two siblings, both alive, are younger brother Joe, a stage actor and former reporter; and older sister Sandy McCain Morgan, a breast cancer survivor.
Running mates, temporarily
Has a vice presidential candidate stepped aside prior to the election?
Yes. Some examples:
• Missouri Sen. Thomas Eagleton was the running mate of Sen. George McGovern, D-S.D., in 1972, until Eagleton's history of hospitalization for depression was revealed.
• While serving as vice president under William Howard Taft, James S. Sherman died before the 1912 election for which he was the Republican Party's vice presidential nominee.
• In 1844, Democrats nominated New York Sen. Silas Wright for vice president. After former President Martin Van Buren, a friend of Wright's, failed to be nominated for another presidential run, Wright refused the nomination.
• Because of his Swiss birth, Albert Gallatin was asked to resign his nomination in 1824 by the Democratic-Republican congressional caucus that nominated William H. Crawford for president.