Education Technology

Estimating and Finding Confidence Intervals

Published on 06/09/2008

Activity Overview

In this activity, students estimate statistical measures and find confidence intervals.

Before the Activity

  • See the attached PDF file for detailed instructions for this activity
  • Print pages 73 - 88 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to the class.

    Follow the Activity procedures:

    Estimating the Mean of a Normal Population:

  • Determine the mean, confidence interval, and margin of error for a sample population with normal distribution
  • Find the critical z value, if the standard deviation (S.D.) is known, otherwise find the t value
  • Observe that the t value > z value


  • Estimating a Population Proportion:
  • Check whether the product of the success percent and the sample size is greater or equal to 10
  • Decide if the normal distribution can be used to approximate a binomial


  • Estimating the Standard Deviation of a Normal Population:
  • Enter a random sample from a population
  • Determine the variance
  • Plot the Chi-Square distribution
  • Check the graph for symmetry
  • Find the critical values
  • Calculate the confidence intervals


  • Estimating the Difference in Two Population Means:
  • Enter random sample data sets as lists
  • Determine the T interval if the standard deviations are unknown, else determine the Z interval
  • Calculate the degrees of freedom, critical t or z values, margin of error, and confidence interval
  • Find the mean of differences and the S.D. of differences


  • Estimating the Difference in Two Population Proportions:
  • Enter the data
  • Calculate the critical z value, and the margin of error
  • Record the percent range in which the difference in population proportions lies


  • Estimators:
  • Pick values from a normal distribution with a mean of 50, S.D. of 10, and variance of 100
  • Obtain an unbiased variance of these values
  • Generate a sequence of 100 sample variances
  • Calculate the mean
  • Plot a histogram
  • After the Activity

    Review student results:

  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary