Confidence-Interval

  • z-Based Confidence Intervals for a Population Mean: Known
  • t-Based Confidence Intervals for a Population Mean: Unknown
  • Confidence Intervals for a Population Proportion
  • Sample size determination

Descriptive Statistics 描述性统计

The science of describing the important aspects of a set of measurements

  • Collect data
    e.g. Survey
  • Present data
    e.g. Tables and graphs
  • Characterize data
    e.g. Sample mean =

Inferential Statistics

The science of using a sample of measurements to make generalizations about the important aspects of a population of measurements.

  • Estimation
    e.g.: Estimate the population mean weight using the sample mean weight
  • Hypothesis testing
    e.g.: Test the claim that the population mean weight is 120 pounds

Estimation

  • Point
    • A point estimate is a single number
  • Interval Estimates
    • a confidence interval provides additional information about variability
Population Parameter Sample Statistic
Mean μ X
Proportion π p

An interval estimate provides more information about a population characteristic than does a point estimate

Such interval estimates are called confidence intervals

Confidence interval

The general formula for all confidence intervals is:

Table Of Contents
Confidence-Interval
Estimation
Confidence interval