Applied Nonparametric Statistical Methods
Transcripción
Applied Nonparametric Statistical Methods
©2001 CRC Press LLC Library of Congress Cataloging-in-Publication Data Sprent, Peter. Applied nonparametric statistical methods.--3rd ed. I P Sprent, N.C. Smeeton. p. cm. -- (Cbapman & Hall/CRC texts in statistical science series) Includes bibliographical references and index. ISBN 1-58488-145-3 (alk. paper) 1. Nonparametric statistics. I. Smecton, N.C. II. Title. III. Texts in statistical science. QA278.8 S74 20W 519.5'4--dc2l 00-055485 This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. 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Visit the CRC Press Web site at www.crcpress.com © 2001 by Chapman & Hall/CRC No claim to original U.S. Government works International Standard Book Number 1-58488-145-3 Library of Congress C~ard Number 00-05.5485 Printed in the United States of America 3 4 5 6 7 8 9 0 Printed on acid-free paper ©2001 CRC Press LLC Contents Preface 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Introducing nonparametric methods Basic statistics Samples and populations Hypothesis tests Estimation Ethical issues Computers and nonparametric methods Further reading Exercises 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Centrality inference for single samples Using measurement data Inferences about medians based on ranks The sign test Transformation of ranks Asymptotic results Robustness Fields of application Summary Exercises 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Other single-sample inference Inferences for dichotomous data Tests related to the sign test Matching samples to distributions Angular data A runs test for randomness Fields of application Summary Exercises 4.1 4.2 4.3 4.4 4.5 Methods for paired samples Comparisons in pairs A less obvious use of the sign test Power and sample size Fields of application Summary Exercises 2 3 4 ©2001 CRC Press LLC 5 Methods for two independent samples 5.1 Centrality tests and estimates 5.2 Rank based tests 5.3 The median test 5.4 Normal scores 5.5 Tests for survival data 5.6 Asymptotic approximations 5.7 Power and sample size 5.8 Tests for equality of variance 5.9 Tests for a common distribution 5.10 Fields of application 5.11 Summary Exercises 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Three or more samples Compaarisons with parametric methods Centrality tests for independent samples Centrality tests for related samples More detailed treatment comparisons Tests for heterogeneity of variance Some miscellaneous considerations Fields of application Summary Exercises 7.1 7.2 7.3 7.4 7.5 Correlation and concordance Correlation and bivariate data Ranked data for several variables Agreement Fields of application Summary Exercises 8.1 8.2 8.3 8.4 8.5 8.6 Regression Bivariate linear regression Multiple regression Nonparametric regression models Other multivariate data problems Fields of application Summary Exercises 7 8 9 9.1 9.2 Categorical data Categories and counts Nominal attribute categories ©2001 CRC Press LLC 9.3 9.4 9.5 9,6 9.7 10 Ordered categorical data Goodness-of-fit tests for discrete data Extension of McNemar's test Fields of application Summary Exercises 10.1 10.2 10.3 10.4 10.5 10.6 Association in categorical data The analysis of association Some models for contingency tables Combining and partitioning of tables Power Fields of application Summary Exercises 11.1 11.2 11.3 11.4 11.5 11.6 Robust estimation When assumptions break down Outliers and influence The bootstrap M-estimators and other robust estimators Fields of application Summary Exercises 11 Appendix References Solutions to odd-numbered exercises ©2001 CRC Press LLC Preface T h e s e c o n d e d i t i o n o f t h i s b o o k w a s w r i t t e n b y th e fi r s t - n a m e d a u t h o r t o pr o v i d e a th e n ( 1 9 9 3 ) up - t o - d a t e in t r o d u c t i o n to n o n p a r a m e t r i c a n d d i s t r i b u t i o n - f r e e m e t h o d s . It t o o k a mi d w a y c o u r s e b e t w e e n a b a r e d e s c r i p t i o n of te c h n i q u e s a n d a de t a i l e d e x p o s i t i o n of th e th e o r y . I n d i v i d u a l me t h o d s a n d li n k s be t w e e n th e m w e r e il l u s t r a t e d ma i n l y b y e x a m p l e s , M a t h e m a t i c s w a s k e p t t o t h e m i n i m u m n e e d e d fo r a c l e a r u n d e r s t a n d i n g o f s c o p e a n d l i m i t a t i o n s . Th e b o o k w a s d e s i g n e d t o me e t t h e n e e d s b o t h o f s t a t i s t i c s s t u d e n t s m a k i n g fi r s t c o n t a c t w i t h t h e s e m e t h o d s a n d o f re s e a r c h w o r k e r s , m a n a g e r s , re s e a r c h a n d d e v e l o p m e n t s t a f f , c o n s u l t a n t s a n d o t h e r s w o r k i n g in v a r i o u s fi e l d s w h o ha d a n un d e r s t a n d i n g of ba s i c s t a t i s t i c s a n d wh o , a l t h o u g h th e y h a d li t t l e p r e v i o u s k n o w l e d g e o f n o n p a r a m e t r i c m e t h o d s , n o w fo u n d o r th o u g h t t h e y mi g h t fi n d th e m u s e f u l in t h e i r w o r k . A p o s i t i v e re s p o n s e fr o m re a d e r s a n d re v i e w e r s h a s e n c o u r a g e d u s t o re t a i n t h e b a s i c fo r m a t w h i l e t a k i n g t h e o p p o r t u n i t y t o i n t r o d u c e n e w to p i c s a s w e l l a s c h a n g i n g th e e m p h a s i s to re f l e c t b o t h d e v e l o p m e n t s in c o m p u t i n g a n d n e w a t t i t u d e s to w a r d s da t a a n a l y s i s . N o n p a r a m e t r i c me t h o d s a r e ba s i c a l l y a n a l y t i c to o l s , bu t da t a c o l l e c t i o n , a n a l y s e s a n d t h e i r i n t e r p r e t a t i o n a r e i n t e r r e l a t e d . Th i s i s w h y we ha v e e x p a n d e d th e c o v e r a g e of to p i c s s u c h a s e t h i c a l c o n s i d e r a t i o n s an d ca l c u l a t i o n of po w e r an d of s a m p l e s i z e s ne e d e d t o a c h i e v e s t a t e d a i m s . Th e s e m a k e t h e i r m a i n i m p a c t a t t h e p l a n n i n g s t a g e , bu t a l s o in f l u e n c e th e a n a l y t i c a n d in f e r e n t i a l ph a s e s . T h e r e h a s b e e n w i d e s p r e a d c r i t i c i s m in re c e n t y e a r s b y ma n y s t a t i s t i c i a n s of in a p p r o p r i a t e a n d e v e n im p r o p e r us e of s i g n i f i c a n c e t e s t s a n d t h e re l a t e d c o n c e p t o f P- v a l u e s . H o w e v e r , t h e s e t o o l s h a v e a p o s i t i v e ro l e w h e n p r o p e r l y u s e d a n d u n d e r s t o o d . To e n c o u r a g e b e t t e r u s e th e s e c t i o n o n h y p o t h e s i s t e s t i n g i n C h a p t e r I h a s b e e n re w r i t t e n , a n d th r o u g h o u t th e bo o k th e r e i s mo r e e m p h a s i s on ho w t h e s e c o n c e p t s s h o u l d be us e d a n d wa r n i n g s a b o u t po t e n t i a l mi s u s e . T h e la y o u t o f C h a p t e r s I to 1 0 fo l l o w s t h e b r o a d p a t t e r n o f t h e c o r r e s p o n d i n g c h a p t e r s in th e s e c o n d e d i t i o n bu t th e r e a r e ma n y c h a n g e s in or d e r a n d ot h e r a s p e c t s of pr e s e n t a t i o n in c l u d i n g ne w a n d m o r e de t a i l e d e x a m p l e s . O n e or tw o to p i c s h a v e be e n dr o p p e d or a r e t r e a t e d in le s s de t a i l , a n d ne w ma t e r i a l ha s be e n in s e r t e d w h e r e a p p r o p r i a t e . As we l l as c o m m e n t s on e t h i c a l co n s i d e r a t i o n s a n d d i s c u s s i o n s on po w e r a n d s a m p l e s i z e , th e r e a r e ne w s e c t i o n s on th e ©2001 CRC Press LLC a n a l y s i s of a n g u l a r da t a , th e u s e of c a p t u r e - r e c a p t u r e me t h o d s , th e m e a s u r e m e n t of a g r e e m e n t be t w e e n ob s e r v e r s a n d s e v e r a l le s s e r a d d i t i o n s . Ex a m p l e s h a v e b e e n c h o s e n fr o m a w i d e r r a n g e o f d i s c i p l i n e s . Fo r a fe w mo r e a d v a n c e d to p i c s s u c h a s re g r e s s i o n s m o o t h i n g te c h n i q u e s a n d M - e s t i m a t i o n we ha v e no t gi v e n de t a i l s of s p e c i f i c me t h o d s bu t on l y a br o a d ov e r v i e w of e a c h to p i c to e n a b l e r e a d e r s to j u d g e w h e t h e r i t ma y b e re l e v a n t t o th e i r p a r t i c u l a r n e e d s . I n s u c h c a s e s re f e r e n c e s a r e g i v e n to s o u r c e s th a t c o n t a i n th e d e t a i l n e e d e d fo r i m p l e m e n t a t i o n . C h a p t e r 1 1 h a s b e e n re w r i t t e n to g i v e a n e l e m e n t a r y in t r o d u c t i o n t o in f l u e n c e fu n c t i o n s , th e n o n p a r a m e t r i c b o o t s t r a p a n d ro b u s t e s t i m a t i o n g e n e r a l l y , a g a i n w i t h re f e r e n c e s to s o u r c e m a t e r i a l fo r t h o s e w h o w a n t to m a k e fu l l u s e o f t h e s e id e a s . M a t e r i a l th a t a p p e a r e d in C h a p t e r 12 of th e s e c o n d e d i t i o n ha s be e n u p d a t e d a n d i n c o r p o r a t e d a t re l e v a n t p o i n t s in th e te x t . W e h a v e n o t in c l u d e d ta b l e s fo r b a s i c n o n p a r a m e t r i c p r o c e d u r e s , m a i n l y be c a u s e mo r e s a t i s f a c t o r y in f o r m a t i o n is pr o v i d e d by mo d e m s t a t i s t i c a l s o f t w a r e , ma k i n g ma n y s t a n d a r d ta b l e s in s u f f i c i e n t or s u p e r f l u o u s fo r s e r i o u s u s e r s o f t h e m e t h o d s . Th o s e w h o n e e d s u c h t a b l e s be c a u s e th e y ha v e no a c c e s s to s p e c i a l i z e d s o f t w a r e a r e we l l c a t e r e d fo r b y s t a n d a r d c o l l e c t i o n s o f s t a t i s t i c a l ta b l e s . W e g i v e r e f e r e n c e s to th e s e th r o u g h o u t th e bo o k a n d a l s o wh e n r e l e v a n t to s o m e s p e c i a l i z e d t a b l e s . W e h a v e re t a i n e d t h e s e c t i o n o u t l i n i n g s o l u t i o n s to od d - n u m b e r e d e x e r c i s e s . W e a r e g r a t e f u l to m a n y re a d e r s o f th e e a r l i e r e d i t i o n s w h o ma d e c o n s t r u c t i v e c o m m e n t s a b o u t th e c o n t e n t a n d tr e a t m e n t , or s o m e t i m e s a b o u t t h e l a c k o f t r e a t m e n t , o f p a r t i c u l a r t o p i c s . Th i s i n p u t t r i g g e r e d m a n y of th e c h a n g e s ma d e in th i s e d i t i o n . O u r s p e c i a l t h a n k s go to J i m M c G a n r i c k fo r h e l p f u l d i s c u s s i o n s o n p h y s i o l o g i c a l m e a s u r e m e n t s a n d to Pr o f e s s o r R i c h a r d H u g h e s fo r a d v i c e o n th e G u i l l a i n - B a r r é s y n d r o m e . W e h a p p i l y re n e w t h e t h a n k s re c o r d e d i n t h e s e c o n d e d i t i o n t o Ti m o t h y P . D a v i s a n d C h r i s T h e o b a l d w h o s u p p l i e d u s w i t h d a t a s e t s u s e d in i t i a l l y i n th a t e d i t i o n fo r e x a m p l e s t h a t w e h a v e re t a i n e d . P. Sprent N. C. Smeeton July 2000 ©2001 CRC Press LLC