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Biostatistics-Repo

BSC 490 - SAS (Statistical Analysis System) Class

TABLE OF CONTENTS

Part 1. Using SAS for Windows 2

Using SAS for Windows	3

Part 2. Homework Assignments 8

Assignment 1: Summary Statistics 9
Assignment 2: Probability & Generating Random Numbers 13
Assignment 3: One and two sample tests 14
Assignment 4: One way Fixed Effects Analysis of Variance & Contrasts 16
Assignment 5: One way Random Effects Analysis of Variance 17
Assignment 6: Two way Factorial Analysis of Variance 19
Assignment 7: Mixed Model Analysis of Variance: Comparing procedures 20
Assignment 8: Two stage Nested Analysis of Variance 22
Assignment 9: Linear & Multiple Regression 23
    Assignment 10:  Analysis of Covariance 24

Part 3. Examples 25

    ANALYSIS OF VARIANCE:  Simulations of the ANOVA model 26
    ANOVA, MULTIPLE COMPARISONS, & CONTRASTS 28
    UNBALANCED ANOVA EXAMPLE 34
    LEAST SQUARES MEANS 41
    ANOVA MODELS WITH RANDOM EFFECTS 47
    NESTED ANOVA 53
    SIMPLE LINEAR REGRESSION 56
    LINEAR & MULTIPLE REGRESSION 65
    ANALYSIS OF COVARIANCE (ANCOVA)	75

INTRODUCTION:

SAS (Statistical Analysis System) is a statistical package designed for data base management and statistical analysis. Biology uses SAS 9.4 for Windows, which is available on
computers in SLB 121 and many of the laboratories in the department. It can be set up to run on any IBM- compatible computer in the department (see me if you need to get it set up in your laboratory). Nearly all internal statements, commands, and procedures are identical to those used in every other version of SAS. The main differences are in the interface that is, the
mechanisms for submitting, calling files, and printing output, and in the on-screen viewing of input and output. The interface for SAS works much like other programs that run in Windows (e.g., Word, Excel). You will find that the Windows version of SAS has a user-friendly interface and program editor. Possibilities for using SAS and interfacing SAS programming with other Windows programs (e.g., Excel, Word, PowerPoint) are numerous and complex, and we will only deal with the simpler aspects of such programming.

This repo is designed to introduce you to the use of SAS in the Windows environment. This repo will NOT teach you to use fully the SAS graphic interface and command language. SAS consists of hundreds of separate procedures, each with 10-200 subcommands and options, plus the DATA step, with hundreds of subcommands, functions, and many variable formats.
There are numerous SAS windows for specialized jobs. It therefore takes much more than a single handout to introduce SAS. The handout gives the minimum information necessary for using SAS on the departmental computers in the computer room (SLB 121). Once you know how to start SAS, use the basic windows, submit, save, and print input and output, and how to get on-line help, you can quickly teach yourself SAS windows, language, and procedures by using on-line help. More information on manuals is given below - sections E.

STARTING SAS:

To start SAS on computers in the Biological Sciences computer room (SLB 121):

  1. The computers should be on, with Windows running.
  2. In Windows, locate the SAS icon on the Desktop or Start menu
  3. Double click

USING SAS

A. The screen. The SAS screen (Fig. 1, next page) is controlled by the DISPLAY MANAGER. There are three windows on the starting screen: the OUTPUT window, in which output of
procedures appears; the LOG window, in which statements submitted for processing, along with error messages appear; and the ENHANCED PROGRAM EDITOR or EPE window, in which you type input statements. Other windows appear as commands are given. SAS for Windows operates much like other Windows programs (e.g., Word, Excel). To move between windows, simply left click on the destination window. You can also enter window names in the command slot (upper left, Fig. 1) and hit ENTER (throughout this handout, keys to be hit will be shown in bold Arial type, SAS screen buttons or menu items to be clicked will be shown in bold Times Roman type). You can tell which window is active by the location of the cursor (which can be hard to see) and by the color of the window banner (top). Any window may be expanded to fill the entire screen by clicking on the icons in the upper right hand corner of each window (Fig. 1) You can shrink a window to an icon by clicking on the little icon with a ‘—’. You can also go to different windows via the VIEW menu.

B. Ways of using SAS. We will cover only one way of using SAS for data entry and analysis: SAS commands and programming, which is not automated and driven mostly by writing code
(as opposed to point-and-click menus). That makes it almost infinitely flexible, but also with a steep learning curve. There are alternative ways of using SAS, however our license does not include them.

SAS commands. SAS is a command driven program. SAS statements are typed in a PROGRAM EDITOR window. They are submitted by hitting the button next to the command slot (the one with the little running man on it…. get it?). You type in the PROGRAM EDITOR, which is a full screen editor (much like Word for Windows). The cursor is moved around the PROGRAM EDITOR window using the mouse, or by using the cursor control keys (Arrows). The PROGRAM EDITOR window allows full-screen editing. Simply type what you want on each line at any point on the screen

Punctuation: SAS has some very specific, very important rules of punctuation.