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