Problem 1: The T-test Demo

WARNING: You must have Xlisp-stat to do this exercise

The UCLA Statistics Department is developing an "electronic textbook", the purpose of which is to offer on-line tutorials to anyone who wants to learn something about statistics. One of these tutorials is the t-test demo . Clicking on this activates a program which displays graphics representing some of the concepts behind the t-test.

You'll notice that the descriptive text is rather sparse. To really understand what's happening here, you must already know what a t-test is. Our goal is to make this a little easier for users who are less sophisticated than we. Here's the problem:

  1. Download xlispstat (Be prepared for frustration!)
  2. Visit the t-test demo. Play around with it. Get a feel for what it does. Pay particular attention to the "Advanced Options" button.
  3. Write a "user's manual" for this program. Imagine you are writing it for someone who is just starting to learn about t-tests in a statistics course very much like our own.
Your user's manual should contain the following:
Background
What is a t-test?
Explanation of graphics
What is the user seeing?
Explanation of buttons and text
What do the buttons do? What does the text mean?
How can I use the demo to understand the principles behind the t-test?
For example, what if I want to understand power better? Or what if I need to choose a sample size so that I can detect if the truth is less than 1/10 of a standard deviation from the hypothesis?
Be creative. The above is only a suggestion, and you can do what you think best. Your only goal is to write something so that someone new to t-tests could sit down at this demo and leave with an idea of what's going on.

If you're curious about more demos, look here.

Rules

Feel free to work in teams, if you wish. Teams should have no more than three people. Each person should write some of the paper themselves. You should write no more than five pages, and fewer is definately allowed.

You may also consult with one another via the Chatroom.

How to Obtain Xlisp-stat

Xlispstat is a lisp-based statistical computing language that is free! If you are using a math department computer, it should already be available. And clicking on the "Student's t test" in the demo should activate it. (If nothing happens, you don't have it.) If you want to do this from your home, then you need to download xlispstat. Documentation, as well as the software itself, is available here .

I have never downloaded xlispstat onto my home computer, and can't offer any advice. If you have trouble, please post a comment to the chatroom. If you were successful, please check the chat room and see if you can offer any advice.

If you have trouble, you should also contact me.

Writing Exercises
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