Chapter 9

Question 1

The statistic, computed from sample information, that estimates a population parameter

Answer 1

Point estimate

Question 2

A range of values constructed from sample data so that the population parameter is likely to occur within that range at a specified probability. The specified probability is called the level of confidence

Answer 2

Confidence interval

Question 3

The central limit theorem allows us to make these two general confidences interval statements using z-statistics

Answer 3

1. 95% of all confidence intervals computed from random samples selected from a population will contain the population mean. These z-values are computed using a z-statistic equal to 1.96
2. Ninety percent of all confidence intervals computed from random samples selected from a population will contain the population mean. These confidence intervals are computed using a z-statistic equal to 1.65

Question 4

How do you determine a 95% or 90% confidence level

Answer 4

xbar + or - 1.96 or 1.65 times sigma/square root of the sample size

Question 5

What is the formula for confidence interval when the population mean is known

Answer 5

xbar + or - z(sigma/square root of sample size)

Question 6

What are 4 characteristics to the t-distribution

Answer 6

1. Like the z distribution, it is continuous
2. Bell shaped and symmetrical
3. There are four t-distributions for different sample sizes
4. T-distributions are more spread out and flatter

Question 7

3 steps to determine the confidence interval for the population mean with an unknown population

Answer 7

1. Assume the sampled population is normal or approximately normal
2. Estimate the population standard deviation with the sample standard deviation
3. Use the t-distribution rather than the z-distribution

Question 8

The fraction, ratio, or percent indicating the part of the sample or the population having a particular trait of interest

Answer 8

proportion

Question 9

Formula for sample proportion when x is the number of successes and n is the number of sampled

Answer 9

p=x/n

Question 10

What two items are needed to develop confidence intervals for a proportion

Answer 10

1. Binomial conditions need to be met
2. The values nΠ should both be greater than or equal to 5

Question 11

The margin of error adjustment needed for finite population

Answer 11

finite-population adjustment
Square root of N-n/N-1

Question 12

Name 3 factors to consider when deciding sample size

Answer 12

1. The margin of error the researcher will tolerate
2. The level of confidence desired
3. The variation or dispersion of the population

Question 13

3 ways to estimate population standard deviation

Answer 13

1. conduct a pilot study
2. use a comparable study
3. Use a range-based approach

Question 14

Sample size formula for estimating the population mean

Answer 14

n=(z*sigma/E)