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Learning SAS by Example by Ron Cody

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Chapter 24. Working with Multiple Observations per Subject

24.1

Introduction

506

24.2

Identifying the First or Last Observation in a Group

506

24.3

Counting the Number of Visits Using PROC FREQ

509

24.4

Counting the Number of Visits Using PROC MEANS

511

24.5

Computing Differences between Observations

512

24.6

Computing Differences between the First and Last Observation in a BY Group Using the LAG Function

514

24.7

Computing Differences between the First and Last Observation in a BY Group Using a RETAIN Statement

515

24.8

Using a Retained Variable to “Remember” a Previous Value

517

24.9

Problems

518

Introduction

You will encounter many data sets with multiple observations per subject (or other groupings such as transactions on a single day or observations grouped in other ...

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