Homework06Solns - Stat 512 2 Solutions to Homework #6 Dr....

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Stat 512 – 2 Solutions to Homework #6 Dr. Simonsen Due Thursday, October 6, 2003 by 4:30pm. Note: I recommend that you attempt these problems before the midterm exam. The material covered by this homework is included on the exam, and doing these problems may help you study. 1. For this problem use the CS dataset examined on Homework #5, and use the model which uses only HSM and HSE as explanatory variables to predict the response GPA. On Homework #5, Problem 6 you examined some visual diagnostics (for your chosen model), which should have included plots of Y vs. X, residuals, etc. Now, additionally examine other diagnostics such as studentized and studentized-deleted residuals, Cook's D, tolerance or vif, and partial residual plots. Explain any problems such as outliers, highly influential observations or multicollinearity that these diagnostics point out. ( Do not include in your output any tables of values for all 224 individuals. Use plots and verbal summaries instead. You may include values for a few selected individuals if you wish.) Studentized and Studentized Deleted Residuals -3 -2 -1 0 1 2 3 1. 3 1. 4 1. 5 1. 6 1. 7 1. 8 1. 9 2. 0 2. 1 2. 2 2. 3 2. 4 2. 5 2. 6 2. 7 2. 8 2. 9 3. 0 3. Pr edi ct ed Val ue of GPA 1 -4 0 1 2 3 Pr edi c t ed Val ue of GPA 3. 1 The Bonferroni-corrected cutoff for studentized deleted residuals are t (1-.05/2n, n-p-1) = 3.75345. No values exceed this threshold since the largest (in magnitude) sdr is -3.01. The above graphs show no unusual features or outliers. The UNIVARIATE Procedure Variable: rs (Studentized Residual without Current Obs) Extreme Observations ------Lowest----- -----Highest----- Value Obs Value Obs -3.01537 188 2.52423 61 Influence Options : The cutoff values for the measures of influence are Obs n p sdr cd hat dff dfb 1 224 3 3.75345 0.79110 0.026786 0.23146 0.13363 Cook’s D : F(0.5, p, n-p) = 0.7911. No values even come close to meeting this threshold since the largest is 0.072.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

Homework06Solns - Stat 512 2 Solutions to Homework #6 Dr....

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online