Chapter 9: Estimating the Value of a Parameter

Level of confidence, (1 - alpha)x100%

Represents the expected proportion of intervals that will contain the parameter if a large number of different samples is obtained.

Critical value

Represents the number of standard deviations the sample statistic can be from the parameter and still result in an interval that includes the parameter.

Point estimate

The value of a statistic that estimates the value of a parameter.

t-interval

A confidence interval about the mean that uses student's t-distribution to determine the critical value.

Robust

A statistical procedure is this if it is accurate despite minor departures from the model requirements, such as normality.

P-hat (Sample proportion), Sampling Distribution of

Expected value of the sampling distribution of P-hat (an estimate of the population proportion): E(p-hat) = p. Variance for the sampling distribution of P-hat: p(1-p) / n. Standard Error(SE) of the Sample Proportion: √ (p(1-p) / n). Note: as the sample size increases, the standard error decreases. You can use the normal distribution if the following two formulas are true: np≥5 n(1-p)≥5. Z Score for sample proportion: z = (P-hat - p) / SE

Confidence interval

For an unknown parameter this consists of an interval of numbers based on a point estimate. Point estimate ± Margin of error A range of values likely to contain an unknown population parameter. L. Limit represents the lower bound on the confidence interval and U. Limit represents the upper bound on the confidence interval. The confidence interval plus the

Nonparametric procedures

Inferential procedures that do not require the data to come from a particular distribution, such as the normal distribution.

Margin of error

It is used to determine the width of a confidence interval. The radius of the confidence interval. The margin of error expresses the maximum expected difference between the true population parameter and a sample estimate of that parameter. To be meaningful, the margin of error should be qualified by a probability statement (often expressed in the form of a confidence level).