Need to knowSAS environmentSAS files (datasets, catalogs etc) & librariesSAS programsHow to:Get data inManipulate dataGet results out

SAS software environment

SAS Windows (SAS 9)

Some (!) SAS windowsEditorWhere code is written or imported, and submittedLogWhat happened, including what went wrongOutputResults of program procedures that produce outputExplorerShows libraries (SAS & Windows), their files, and where you can see data, graphs ResultsShows how the output is made up of tables, graphs, datasets etcNotepadA useful place to keep bits of code

SAS software programs

SAS Programsdata one;input x y;datalines;-3.2 0.0024-3.1 0.0033. . . ;run;

proc print data = one (obs = 5);run;

proc means data = one;run;

DATA stepcreates SAS data setPROC stepsprocess data in data set

Step BoundariesSAS steps begin with aDATA statementPROC statement.

SAS detects the end of a step when it encountersa RUN statement (for most steps)a QUIT statement (for some procedures)the beginning of another step (DATA statement or PROC statement).Recommendation: use RUN; at end of each step

data seedwt;input oz $ rad wt;datalines;Low 118.4 0.7High 109.1 1.3Low 215.2 2.9run;

proc print data = two;

proc means data = seedwt; class oz; var rad wt;run;Step Boundaries

Submitting a SAS ProgramWhen you execute a SAS program, the output generated by SAS is divided into two major parts: SAS log contains information about the processing of the SAS program, including any warning and error messages.SAS output contains reports generated by SAS procedures and DATA steps.

Recommended steps!Submit all (or selected) code byF4Click on the runner in the toolbarRead logLook in output window if you expect code to produce outputProblemsBad syntaxMissing ; at end of lineMissing quote at end of title (nasty!)

Improved output - HTMLTools Options Preferences Results Do this & resubmit codeCheck HTML output in Results Window

SAS data sets

SAS data setsSAS procedures (PROC ) process data from SAS data setsNeed to know (briefly!)What a SAS data set looks likeHow to get out data into a SAS data set

SAS data setslive in librarieshave a descriptor part (with useful info)have a data part which is a rectangular table of character and/or numeric data values (rows called observations)have names with syntax datasetname libname defaults to work if omitted

work librarySAS data sets with a single part name like oz, wp or mybestdata99are stored in the work librarycan be referenced e.g. as mybestdata99 or work.mybestdata99are deleted at end of SAS session!

Dont loose your data!Keep the SAS program that read the data from its original source

. . . More later!

Viewing descriptor & data/* view descriptor part */proc contents data = wp;run;/* view data part */proc print data = work.wp;run;Alternatively:Use SAS Explorer: Open (for data) Properties (for descriptor)Properties is not as clear as CONTENTS

SAS variablesThere are two types of variables:charactercontain any value: letters, numbers, special characters, and blanks. Character values are stored with a length of 1 to 32,767 bytes (default is 8). One byte equals one character.

numericstored as floating point numbers in 8 bytes of storage by default. Eight bytes of floating point storage provide space for 16 or 17 significant digits. You are not restricted to 8 digits. Dont change the 8 byte length!

SAS variables The CONTENTS Procedure

Alphabetic List of Variables and Attributes

# Variable Type Len 1 oz Char 8 2 rad Num 8 3 wt Num 8OUTPUT

SAS names for data sets & variablescan be 32 characters long.can be uppercase, lowercase, or mixed-case but are not case sensitive!must start with a letter or underscore. Subsequent characters can be letters, underscores, or numeric digits - no %$!*@ or spaces.

Missing Data ValuesLastName FirstName JobTitle Salary

TORRES JAN Pilot 50000LANGKAMM SARAH Mechanic 80000SMITH MICHAEL Mechanic . WAGSCHAL NADJA Pilot 77500TOERMOEN JOCHEN 65000A value must exist for every variable for each observation.Missing values are valid values.A numeric missing value is displayed as a period.A character missing value is displayed as a blank.

SAS syntaxNot case sensitiveEach line usually begins with keyword and ends with ;Common Errors:Forget ;Miss-spelt or wrong keywordMissing final quote in titletitle Woodpecker Habitat; /* quote mark missing */title Woodpecker Habitat;

CommentsType /* to begin a comment.Type your comment text.Type */ to end the comment.To comment selected typed text remember: Ctrl+/Alternative:* comment ;

Statistics in Science

SASCreating a SAS data set

Getting data in!Consider 2 methodsData in program (briefly!)Data in Excel workbook

Getting data in!Data in program file:data oz;input oz $ rad wt;datalines;Low 118.4 0.7High 109.1 1.3Low 215.2 2.9. . .;run;Note:oz is text variable so requires $No missing valuesValues of oz dont contain spacesare at most 8 character long

Getting data in!from Excel

Use IMPORT wizard saving program to reduce future clicking!

Creating new variablesAdding a new variable to an existing SAS data set (say work.old)Use setGive definition of new variable data new; /* read data from work.old */ set old; y2 = y**2; ly = log(y); ly_base10 = log10(y); t1 = (treat = 1); run;

Data set: work.new

Data Screening

Data Screeningchecking input data for gross errorsUse PRINT procedure to scan for obvious anomaliesUse MEANS procedure & examine summary tableMAXIMUM, MINIMUM reasonable?MEAN - near middle of range?MISSING VALUES - input or calculation error e.g. log(0)?CV (= 100*std.dev/mean) - < 10% for plant growth, between 12 & 30% for animal production variables, > 50% implies skewness for any positive variable

SAS syntaxMEANS syntax

What else should go here?

Dealing with data errorsCheck original recordsChange mistakes in recording where the correct value is beyond questionRegenerate observations where possible e.g. reweigh sample, redo chemical analysisWith a large body of data in an unbalanced design err on the side of omitting questionable dataDo not proceed until data has been properly cleaned if necessary perform a number of screening runs

Open wp.sas for illustrationDo a few example using wp.sasDo demo with wp.sas using contens and ExplorerSee program rd_oz.sas:Check long value for ozvalue with spaceDo demo using oz.xls