Biostatistics & SAS programming. Kevin Zhang

Transcription

1 Biostatistics & SAS programming Kevin Zhang January 26, 2017 Biostat 1

2 Instructor Instructor: Dong Zhang (Kevin) Office: Ben Franklin Hall 227 Phone: dzhang(at)bloomu.edu Class web: Grading: Homework (10%), Lab assignments (15%), 3 midterms (15% each), comprehensive final (30%) January 26, 2017 Biostat 2

3 Lecture + Lab Organization Lectures on Tuesday classes introduce new content Lab assignments on Thursday classes to review and practice the techniques Content Motivation of the methodology Math background The algorithm SAS programming Result interpretation January 26, 2017 Biostat 3

4 Start SAS SAS is installed on VM on campus and we can use it remotely This allows us to use SAS anywhere with our ID. January 26, 2017 Biostat 4

5 Start SAS Domain\Username: BUAD\Your_Husky_ID Password: Your Husky password Logout: Click the Sign out on top right January 26, 2017 Biostat 5

6 Start SAS Click the SAS icon, a remote desktop connection will be downloaded Double click the connection. January 26, 2017 Biostat 6

7 Start SAS January 26, 2017 Biostat 7

8 Start SAS Well, another logon to the remote server. Again, typing your Husky password. January 26, 2017 Biostat 8

9 Meet with SAS system Output window, to view analysis result here Explorer allows you to view datasets and libraries Editor window. Write your code here January 26, 2017 Biostat 9

10 Data set!? There are three ways to get the data into SAS: Type the values manually DATA step Read existing data files DATA step or IMPORT proc Fetch data from remote database SQL proc January 26, 2017 Biostat 10

11 STEP vs PROC!? In SAS program, we have three components: DATA step: Used to handling dataset: Reading the data, Merging data, Stacking data, or other operations. We always use DATA step the prepare the dataset for the analysis PROC PROC step: Analyze the prepared data to obtain results. SAS provides many procedures (proc) to perform different analysis MACRO: Macro allows us to pool all related analysis together, and you may use macro to create your own algorithm. January 26, 2017 Biostat 11

12 DATA step Let play with the following code: data tmp; input x y; cards; ; run; Click to run January 26, 2017 Biostat 12

13 DATA step The code create a new data set named tmp in the default library (The library can be a folder containing all related data sets of your project). The default library in SAS is Work, when we close the SAS system, it will be cleaned. January 26, 2017 Biostat 13

14 First PROC Typing the following code after your DATA step and run your code again proc print data=tmp; run; January 26, 2017 Biostat 14

15 In SAS, the variable will be Numbers Default type String Date -- Do not use it frequently Variable type January 26, 2017 Biostat 15

16 data tmp1; input name$ score; cards; AAA 100 BBB 80 CCC 120 DDD 190 ; run; Example 1.2 What happens if you use name only? proc print data=tmp1; run; January 26, 2017 Biostat 16

17 DATA step Some details In previous examples, we input the values manually. Thus there is a statement input to tell SAS the variable name and type. input is looking for cards block containing our values in the same pattern of provided variable names. The data block do NOT need semi-comma (;) To terminate the imputation, a semi-comma (;) in the end of cards block will be sign can be used to pool several lines in one line data tmp1; input name$ score@@; cards; AAA 100 BBB 80 CCC 120 DDD 190 ; run; January 26, 2017 Biostat 17

18 PROC step Some details Start with proc always, followed by the procedure name you want, such as print In the same line, a data= option is needed to let SAS know which dataset you will play with In the future, there will be some options, like confidence level, significant level, graph settings, will be placed here in the same line In the body of proc we can specify the variable(s) we want to analyze, and options for your analysis. proc print data=tmp1; var name; run; Instead of viewing all variables, we check name only January 26, 2017 Biostat 18

19 Run; Some details A run; statement is to submit your code block to SAS. Some special proc may need quit; but not run; such as proc sql to terminate the connection to the database. January 26, 2017 Biostat 19

20 Import existing datasets In most cases, we will receive datasets in Excel sheet or Plain text format such as CSV, TXT, or DAT There are always hundreds or thousands of records, and therefore it is not possible to input manually using DATA step SAS provides flexible interface for us to import the given data easily. January 26, 2017 Biostat 20

21 Importing Graphical way Click File Choose Import Data Choose the format of your data file January 26, 2017 Biostat 21

22 Importing SAS proc import You can simply change following code to import the CSV files. PROC IMPORT OUT= TMP2 DATAFILE= "P:\MyDoc\CourseLectureNotes\BioStat\Lecture01\Ex01.csv" DBMS=CSV REPLACE; GETNAMES=YES; RUN; OUT= specify the dataset name in SAS to save your imported file You can change the file path above for other files. January 26, 2017 Biostat 22

23 Homework Please review the examples, then import the Ex3.csv file to SAS using either graphical way or proc way. Print the content of Ex3. Print only Age variable in Ex3. Print Salary and Edu in Ex3. January 26, 2017 Biostat 23