// File New-Lec2-01-04-01-03.txt. Edition 7/14/2010. // Lab Specs // Window Title Random_Influences_-_Error_Terms // List of Error Variances 50. 500. 150. 500. // List of Heter Values -2.0 2.0 1.0 .0 // List of Rho's -.9 .9 .3 .0 // List of XECorr's -.9 .9 .3 .0 // Problem Specs // Hetero visible (0 not visible, -1 visible) // Rho visible (0 not visible, -1 visible) // XECorr visible (0 not visible, -1 visible) // Graph visible (0 none, -1 et versus et-1, 1 e versus x) // Pause checked (0 not checked, -1 checked) // ErrVar value // Hetero Factor value // Rho value // XECorr value ` 0 0 0 0 -1 500 0 0 0 Two Objectives: _ First, show that the error term is a random variable; that is, we cannot predict the value of a student's error term before the quiz is given. _ Second, show that the mean of the error term's probability distribution equals 0; that is, after many, many repetitions the average of each student's error term is about 0. ` 0 0 0 0 -1 500 0 0 0 1. Click Start. Three histogram's appear at the top of the window. One histogram for student 1's error term, one for student 2's error term, and one for student 3. Record the numerical value of each student's error term? _ 2. Next, click Continue; note that the means (averages) of the numerical values of each student's error terms are reported below the histograms. Are the means being calculated correctly? ` 3. Click Continue a few times. Before a quiz is given, can you predict the numerical value of a student's error term? Explain why this suggests that the error term is a random variable. _ 4. Now, clear the Pause checkbox and click Continue. After many, many repetitions click Stop. What is the mean of each student's error terms? _ 5. Does the simulation capture random influences? Explain.