Question: How informative is a poll? In this presidential election season, many different polls are conducted for various purposes. Let’s make inference based on the results of a poll, and evaluate how informative the poll is.

a. Select a poll, related to the presidential election, with complete results from a public resource. Decide a parameter of your interest (a population proportion towards a certain candidate). Clearly state the following elements:

Source of data:

Date of the poll:

Data collection detail, if available:

Population:

Parameter:

Sample size:

Value of statistic:

Here is an example: Right after the first presidential debate, CBS News conducted an instant poll on who won the debate.

Source of data: CBS News. http://www.cbsnews.com/video/watch/?id=7424218n

Date of the poll: Oct. 3, 2012

Data collection detail, if available: CBS News and GFK's knowledge panel recruited 523 uncommitted voters to determine the winner of the first presidential debate between President Obama and Mitt Romney. Forty six percent thought Governor Romney won the debate and 22 percent thought Mr. Obama did.

Population: All uncommitted voters in US.

Parameter: The proportion among all uncommitted voters who thought Governor Romney won the debate.

Sample size: 523

POLL CHOSEN FOR ASSIGNMENT:

Poll: Joe Biden wins vice presidential debate

Source of data: CBS News http://www.cbsnews.com/video/watch/?id=50132981n

Date of the poll: October 11, 2012

Data collection detail, if available: CBS News and GFK’s knowledge panel put together a scientifically selected sample of about 500 uncommitted voters, to determine which candidate did the best job or won the vice presidential debate. 50% percent thought Joe Biden won, 31% thought Paul Ryan won.

Population: All uncommitted voters in the U.S.

Parameter: The proportion of uncommitted voters who thought Joe Biden won.

Sample size: 500 uncommitted voters

Value of statistic: The sample proportion of those who thought Joe Biden won is 50%

b. Find and interpret a 95% confidence interval of the parameter of your interest.

c. Based on the confidence interval, do you think the population dominatingly favors one candidate?