Statistical Methods and Computing 22S 30 105 Instructor Cowles Lab 1 Jan 25 2006 1 If you want SAS for your own computer SAS for Students Windows version is available at a reduced cost of 45 00 for students using the software for academic purposes This license needs to be renewed in October Available at the IMU Bookstore See the SAS Information page http www cs its uiowa edu software sas shtml for product information 2 Getting started in the ITC ITC computers will display a login screen Users should enter their HawkID and password in the spots provided Students can find their HawkID and default passwords on the ISIS system 3 Downloading files from the course web page In the save as dialog box chose My ComputerLocal Disk C Temp Click Save If you preferred to save the file on your own disk in drive A so that you could use it on a different computer later you would move to drive A in the dialog box before saving Left click the billion info file to read a description of the billion dataset Click Back to get back to the list of datasets Then download the file billion dat according to the directions above 4 Other useful features on the course web page Return to the main course web page and click Web resources Note that there is a directory of the locations and hours of all the campus ITCs as well as a link to the Mathematical Sciences Library electronic reserve where solutions will be posted Lecture notes homework assignments and lab handouts are posted under Handouts These are in a format that may be read and printed in most ITCs 5 Accessing SAS Click on Start All Programs SAS SAS 9 1 English You will get a screen that shows Bring up a web browser either Firefox or Internet Explorer Enter the address of my web page in the location box a menu bar a log window www stat uiowa edu kcowles a program editor window Then click on Course homepages and 22S 30 105 Click on Datasets and when the next screen appears click on the underlined link Datasets Three types of files may be accessed Files ending in dat are data files for your use with the software package SAS Files ending in info contain descriptive information about datasets Files ending in txt are datasets for use in a different class with a different software package Note that this list is case sensitive with all files with names beginning with capital letters appearing before all other files To download a data file for use in this lab Right click the file name use the right not left mouse button In the dialog box that opens left click Save target as use the left mouse button 1 6 Entering commands and programs Click in the program editor window You may now type commands and programs in this window 7 How SAS programs and commands are organized Use a DATA step to organize your data by creating a SAS dataset Then use PROC steps or automated features to analyze your data Once you have created a SAS dataset you may apply any SAS procedures or automated features to it during the SAS session without recreating the dataset DATA and PROC steps consist of SAS statements Each statement must end with a semicolon Most statements include one or more keywords that must be spelled exactly as shown 2 8 The DATA step Creating a SAS dataset Before it can process data SAS must read in the data in the form of a table with a row for each observation infile a billion dat 11 Using SAS procedures to list and tabulate the dataset Once the dataset is created you may run SAS procedures to analyze it To list the entire dataset a column for each variable You must choose a name for the entire dataset and a name for each variable SAS has the following rules for names SAS names must begin with a letter or an underscore The remaining characters in a SAS name can be letters numbers or underscores There must be no embedded blanks SAS distinguishes between two types of variables numeric variables which contain only digits and decimal points and with which arithmetic operations may be done and character variables all other kinds of data proc print data billion run To get a frequency distribution of the regions in which billionaires lived proc freq data billion tables region tables is a keyword region is the name of the variable for which you want counts run The output is The FREQ Procedure 9 Controlling print width Cumulative Cumulative region Frequency Percent Frequency Percent A 38 16 31 38 16 31 E 80 34 33 118 50 64 M 22 9 44 140 60 09 O 29 12 45 169 72 53 U 64 27 47 233 100 00 Put this line at the beginning of every SAS program if you want output to print correctly on 8 1 2 by 11 inch paper options linesize 75 10 Reading data in from an existing datafile You have saved the file billion dat in the temp directory Use an infile statement to tell SAS to use it 12 data billion infile c temp billion dat input wlth age region Use proc univariate for quantitative variables when you want the following run gives dataset a name for SAS tells SAS where the data is names the variables in each row after region identifies character vbl end of data step Type these lines into the program editor window To make SAS run these statements and create the dataset use the mouse to highlight the block of statements and then click on the icon of the running man SAS will use the log window to tell you what it has done Be sure to check the log window for any error messages If any errors are reported click in the program editor window to make it active Correct the errors in the code and then rerun the block of code Note if you wanted to read in the file from your own disk in the A drive the infile statement would be 3 Proc univariate SAS workhorse of descriptive statistics means medians quartiles 5 number summary stem plots for small datasets or histograms large datasets boxplots proc univariate plot data billion var wlth run 4 The output is 25 Q1 10 5 1 0 Min The UNIVARIATE Procedure Variable wlth 1 3 1 1 1 0 1 0 1 0 Moments N Mean Std Deviation Skewness Uncorrected SS Coeff Variation 233 2 68154506 3 31884032 6 57544276 4230 84 123 765972 Sum Weights Sum Observations Variance Kurtosis Corrected SS Std Error Mean 233 624 8 11 0147011 56 9655987 2555 41064 0 21742446 Basic Statistical Measures Location Mean Median Mode Variability 2 681545 1 800000 1 000000 Std Deviation Variance Range Interquartile Range 3 31884 11 01470 36 00000 1 70000 Tests for Location Mu0 0 Test Statistic p Value Student s t Sign Signed Rank t M S Pr t Pr M Pr S 12 33323 116 5 13630 …