Introductory Biostatistics

(a)Arrange the data onnodesandx-rayinto a 22 table, calculate the

odds ratio associated with x-ray and give your interpretation.

(b)Arrange the data onnodesandgradeinto a 22 table, calculate the

odds ratio associated with grade and give your interpretation.

(c)Arrange the data onnodesandstageinto a 22 table, calculate the

odds ratio associated with stage and give your interpretation.

If you use Microsoft’s Excel to solve this problem, 22 tables can be

formed usingPivotTable Wizardin theData menu. An SAS program for

part (a), for example, would include these intructions:

PROCFREQ;

TABLESNOTES*XRAY/OR;

TABLE E1.46 Prostate Cancer Data

X-

ray Grade Stage Age Acid Nodes

X-

ray Grade Stage Age Acid Nodes

0116440000060780

0016340000052830

1006546000167950

0106747000056980

0 0 0 66 48 0 0 0 1 61 102 0

0 1 1 65 48 0 0 0 0 64 187 0

0006049010158481

0005149000165491

0006650011157511

0005850001050561

0105650011067671

0016150000167671

0116450001157671

0005652001145701

0006752000146701

1004955010151721

0115255011160761

0006856011156781

0116659011150811

1006062000056821

0006162000163821

1115963011165841

0005165010164891

0115366001059991

0 0 0 58 71 0 1 1 1 68 126 1

0 0 0 63 75 0 1 0 0 61 136 1

00153760

Note:This is a very long data file; its electronic copy is available in Web-based form from

the author upon request. Summaries would be formed easily using simple computer soft-

ware.

56 DESCRIPTIVE METHODS FOR CATEGORICAL DATA