BUS 245 Exam 3

the standard error of the mean

- is never larger than the standard deviation of the population - decreases as the sample size increases - measures the variability of the mean from sample to sample

In general, the control limits of a control chart are set at __________ standard deviations from the centerline.

3

the central limit theorem is important in statistics because

for a large n, it says the sampling distribution of the sample mean is approximately normal, regardless of the shape of the population

A t distribution

has slightly broader tails than the z distribution

suppose you are constructing a confidence interval for the population mean. for a given sample size and standard deviation, the width of the interval is wider for a

higher confidence level

A sample statistic is considered biased if

it systematically over- or under-estimates the unknown parameter being estimated

tdf distribution is used when the

population variance is unknown

proportion

qualitative data

mean and standard deviation

quantitative data

confidence interval narrows if

sample size increases the chosen confidence level decreases

precision in interval estimate is implied by a(n) ___________ margin of error

small

What kind of sampling is more likely to be used by political pollsters who want to ensure that each religious group is represented in the sample?

stratified random sampling

the purpose of statistical quality control is to

maintain high-quality goods and services

the width of a confidence interval estimate for a proportion will be

narrower for 90% confidence than for 95% confidence

if we were to sample repeatedly from a given population, the average value of the sample means will equal

the population mean

The greek letter _______ denotes the level of significance

a

estimate

a particular value of an estimator

the central limit theorem states that, for any distribution, as n gets larger, the sampling distribution of the sample mean becomes

closer to normal distribution

parameter

constant

two main components of confidence interval

point estimate and margin of error

statistic

random variable

A simple random sample is a sample of observations that is

representative of the population from which it is chosen