The applet poses a random word problem about confidence intervals for the mean of a normal distribution. The user enters the steps of the solution in a series of boxes. The applet checks the solution to each step and gives hints as needed. Once the right solution to the step is entered, the applet goes to the next step. Besides the word problem, the site also provides two written theoretical exercises on confidence intervals. There is a web page with information about finding point estimates and confidence intervals for both large and small samples.
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This applet is designed to foster a good understanding of confidence intervals using the central limit theorem.
Target Student Population:
Students in statistics courses at the college level.
Prerequisite Knowledge or Skills:
Familiarity with confidence intervals for the normal distribution.
Type of Material:
Tutorial. May also be suitable for classroom discussion.
The word problems can be used in a classroom setting or independently. The written exercises can be done independently.
It requires a "Java-enabled" browser.
Evaluation and Observation
The content about confidence intervals is very accurate. It is presented very clearly. The purpose of the applet is to reinforce the steps needed in developing the confidence interval for the mean of large samples. With this in mind, all the problems are concise and similar in organization of information so that the student can concentrate on completing the steps.
All of the examples/problems use large samples. The author has included a statement in the applet that the sample standard deviation may be assumed equivalent to that of the population?s. This applet is then appropriate for those elementary statistics texts that use the z values for large samples regardless of knowledge of the population?s standard deviation, and for those that use the z values only when the population?s standard deviation is known.
Problems that use small samples could be added as they are covered in the documentation. The symbol zc in the z table does not follow the standard notation in statistics.
Potential Effectiveness as a Teaching Tool
By using word problems, the concept of hypothesis testing is presented very clearly and effectively. The solution to the problem is entered step by step. It is possible to request hints, thus making it easier to work the problem. If a wrong input is entered, the applet opens a prompt with either a hint or the type of error committed. In this way, users can find where and why their solution to the problem is wrong. All of the problems are clearly stated and appropriate for any undergraduate statistics course.
Ease of Use for Both Students and Faculty
The applet is easy to use. The display is aesthetic and visually attractive. The feedback about wrong solutions and hints makes the applet very easy to work with.