Effect of Sample Size on Variability Amongst Samples

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Presentation transcript:

Effect of Sample Size on Variability Amongst Samples

Samples of sizes 100 and 200 2500 Samples of 100 per sample

Samples of sizes 400 and 800 2500 Samples of 400 per sample

Samples of size 1600 and 3200 2500 Samples of 1600 per sample

Bradley In Dead Heat With Gore In NH, Poll Shows Updated 11:03 AM ET September 5, 1999 BOSTON (Reuters) - Bill Bradley is in a statistical dead heat with Vice President Al Gore in the race for the Democratic presidential nomination in the key primary state of New Hampshire, a poll released Sunday by the Boston Globe and WBZ-TV found. "The Democratic primary race really appears to be a race that could go either way," Gerry Chervinsky, president of KRC Communications, which conducted the survey of 800 likely voters, told the Globe. Among those surveyed between Aug. 27 and Aug. 31, Gore led Bradley, the retired New Jersey senator, by 40 percent to 36 percent -- a statistical tie because the poll's margin of error was plus or minus 5 percentage points, the Globe said. Other recent surveys showed Gore with a larger, albeit shrinking, lead over his only Democratic challenger for the party's presidential nomination.

A New Twist Estimate the population percent for the population from which these samples were taken Estimate the size of the samples

Another new twist A large number of samples will be taken from some population. It is okay that the samples are distributed around the population percent about as above. Approximately how large may the samples be? Support your answer. (Use existing data from recent activities.)