Module 5: Confidence Intervals

Vocabulary flashcards covering key terms from Module 5 notes on confidence intervals.

Confidence interval

An interval of numbers around a point estimate within which the population parameter is believed to fall.

Point estimate

A single best guess for a population parameter (e.g., π̂ or ȳ) used to center the confidence interval.

Parameter value

The true value of the population parameter (e.g., π or μ) that the interval aims to capture.

Sample size (n)

The number of observations in a sample.

Sample proportion (π̂)

The proportion of successes in the sample; used to estimate the population proportion π.

Population proportion (π)

The true proportion of the population with a given characteristic.

Sample mean (ȳ)

The average value of the sample; used to estimate the population mean μ.

Population mean (μ)

The true average value of the population.

Sample standard deviation (s)

The standard deviation calculated from the sample data.

Population standard deviation (σ)

The true standard deviation of the population.

Z-score

Critical value from the standard normal distribution used in confidence interval calculations for large samples (e.g., z ≈ 1.96 for 95%).

T-score

Critical value from the t distribution used when the population standard deviation is unknown and the sample size is small.

Margin of error (M)

The maximum expected difference between the sample statistic and the population parameter; added to/subtracted from the point estimate to form the CI.

Lower bound

The left endpoint of a confidence interval.

Upper bound

The right endpoint of a confidence interval.

Simple random sample

A sampling method where every member of the population has an equal chance of being selected.

95% confidence interval

An interval constructed so that, in repeated sampling, 95% of such intervals would contain the true population parameter.

99% confidence interval

An interval constructed so that, in repeated sampling, 99% of such intervals would contain the true population parameter.

Round up

Always round the required sample size upward to ensure the desired margin of error.