**Normal Approximation to the Binomial Distribution

This demonstration allows you to view the binomial distribution and the normal approximation to it as a function of the probability of a success on a given trial and the number of trials. It can be used to compute binomial probabilities and normal approximations of those probabilities.
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Author Name: 
David M. Lane
Technical Requirements: 
Java enabled browser
Content Quality Concerns: 
The material uses capital "N" for the sample size which may not align with the more typical "n" that is used in most statistics textbooks. The supporting materials also use "M" for the mean of a population which may confuse some students. It would be helpful to see more exercises illustrating when the approximation is appropriate.
Content Quality Strengths: 
Nice graphical representation of the probability being estimated. Good definition of the central limit theorem and discussion about the continuity correction with an example. Provides a reasonable presentation of the binomial approximation.
Ease of Use Concerns: 
This applet presents in a rather small form that is to be expected given the age of the applet. It is readable by a person sitting at a computer monitor but it would be difficult to use for classroom presentation on a large overhead projector. The applet also has a problem in that the upper line of text is obscured by the window border. This occurred for the reviewer in both Mozilla and Internet Explorer on a PC.
Ease of Use Strengths: 
This applet has very clear instructions and it is very easy to use. The item is visually engaging and interactive.
Potential Effectiveness Concerns: 
The main weakness of this material is age. It was created many years ago and has some features that are clearly dated. The supporting materials provide exercises that are simply text. They lack interactivity or even answers. The questions themselves do not necessarily encourage the students to use the applet component of the calculator. For instance the exercises include this question: "1. Two equally matched baseball teams play six games. What is the probability that each will win three games?". There is nothing inherent in this question that would drive a student to use the applet or even the normal approximation to the binomial. Another question asks: "4. What is the relationship between N and how well the normal distribution approximates the binomial distribution." (sic) This question does not lead the student to experiment with the applet to discover the relationship. This question could be greatly improved by giving students several values of N to experiment with, then asking them to summarize the result. It should also be noted when it is appropriate to use the normal approximation to do binomial probabilities.
Potential Effectiveness Strengths: 
This material does a reasonable job of graphically presenting the binomial approximation.
Content Quality Rating: 
Ease of Use Rating: 
Potential Effectiveness Rating: 
Source Code Available: 
Source Code Available
Intended User Role: 
Learner, Teacher
Resource Type: 
Free for All

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