Introduction To Correlation with SAS Sam Gordji Weir 107

List of Statistical Packages Available through OIT SPSS (Windows) SAS (Windows & Unix) Mathematica (Windows) Matlab (willow, Unix) Free PGI Fortran compiler

General Information IT staff will assist users –To access these packages –To find the proper procedure to analyze their data For assistance please

Correlation with SAS This seminar covers correlation with SAS SAS is available in –Weir Student Lab (4 PCs) –Weir 107 –Several other labs around campus SAS is also installed on willow (Unix server) SAS performs statistical analysis including procedure correlation

Statistical Package: SAS/PC (cont.) 50 copies are available for faculty use For each copy purchased, a faculty member can get a free copy (to be installed on a student PC) The cost is $200 per copy per year (starting Aug. 2009) To obtain a copy of SAS please

Installation of SAS To obtain a DVD for SAS send an to: The instruction for installation will be ed to you

Links for SAS The main webpage For information on documentation for SAS visit SAS Resources for Faculty and Students:

SAS’ Three Main Files *.sas (a SAS program file created by the user, an input file) *.log (a file created by SAS containing the “log” after the user’s program is finished running) *.lst (a file containing the output) Examples of the three SAS files –my.sas –my.log –my.lst

Running SAS on Windows Click on the “SAS” icon to activate SAS Create your program (below) in a window named “Editor- Untiled1” Blue Text is your program /* comments go between slashes and stars */ data test; /* every SAS program starts with “data”, test is a given name for this program */ input a b c; /* variables are a, b, and c */ cards; /* input data will follow “cards” */ 1 2 3/* variable a has 2 observations, 1 and 2 */ /*variable b has 2 observations, 2 and 3, and so on */ ; /* semicolon signals the end of the data */ proc print; proc means; /* proc print prints the data, proc means obtains several statistics including the mean */ run; /* run, runs the program */

Running SAS on Windows User’s SAS Program Click “run” and then “submit” the above example

Running SAS on Windows listing file (output of SAS) Input data: Results:

Running SAS on Windows SAS log file first 3 lines of the user’s input Lines 6 & 7 end data & proc print Lines 7 & 8 proc means & run

Correlation Correlation coefficient measures the relationship between two variables The correlation coefficient is always between -1 and 1, -1.0<=C<=1.0 Values near 0 are indication of no relationship and values near 1 indicate a strong relationship between the variables Negative values indicate negative relationship

An Example of Correlation corr748re.sas Below is an example of correlation analysis Data is entered into “Editor” Download corr748re.sas program below from:

Output from Correlation Analysis

Non-parametric Correlation Proc corr also performs non- parametric correlation Proc corr below performs non- parametric correlation and obtains Spearman, Kendall Tau, and Hoeffding correlation

Non-parametric Correlation

Non-parametric Correlation Assumes That the Input Data Is Non-Parametric Pearson Spearman Kendall Tau

Some SAS Proc Proc (Procedure) –proc means (obtains mean, standard deviation) –proc anova (performs simple AOV) –proc plot (plots) –proc lp (performs Linear Programming) –proc reg ( performs regression) –proc corr (performs correlation)

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For Further Practice Go to – agename=jancamp09_sam.inchttp:// agename=jancamp09_sam.inc download and run the following examples –mort1.sas –mem_corr.sas