Using Stata For Principles of Econometrics . Third Edition I ·1· I ! t . i: f, I Lee Adkins dedicates this work to his lovely and loving wife, Kathy , Carter Hill dedicates this work to Stan Johnson and George Judge - ' , . Bicentennial Logo Design: Richard 1. Pacifico Copyright @ 2008 John Wiley & Sons, Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical