Chapter 8

critical value

Multiplier that makes a confidence interval wide enough to have the stated capture rate. The critical value depends on both the confidence level C and the sampling distribution of the statistic.

margin of error

The difference between the point estimate and the true parameter value will be less than the margin of error in C% of all samples, where C is the confidence level.

one-sample z interval for a proportion

Confidence interval used to estimate a population proportion.

confidence interval

Gives an interval of plausible values for a parameter. The interval is calculated from the data and has the form point estimate � margin of error or, alternatively, statistic � (critical value) ? (standard deviation of statistic)

confidence level C

Success rate of the method for calculating the confidence interval. In C% of all possible samples, the method would yield an interval that captures the true parameter value.

point estimate

Specific value of a point estimator from a sample.

point estimator

Statistic that provides an estimate of a population parameter.

Random condition

A condition for performing inference, which requires that the data come from a random sample from the population of interest or from a randomized experiment.

Normal/Large Sample condition

A condition for performing inference about a mean, which requires that the data come from a Normally distributed population or that the sample size is large (n ? 30 ).

one-sample t test for a mean

A test of the null hypothesis that a population mean is equal to a specified value.

standard error

When the standard deviation of a statistic is estimated from data, the result is the standard error of the statistic.