An Introduction to SYSTAT
1. Creating Data/Importing/Saving Data
To create data, click File->New->Data, and enter the dataset. You can also import data by using
File->Open->Data. The supported file formats for import include Excel, SPSS, SAS, MINITAB,
and JMP. Once inputted, data can be saved in the SYSTAT file format.
2. The SYSTAT user interface
The organization of the user interface is somewhat complicated. The command window is a .syc
file that appears at the bottom of the screen. SYSTAT outputs the results of commands in a .syo
file, which is accessible by clicking on a tab toward the top of the screen. Any graphics are also
outputted to a separate tab. SYSTAT stores the results of user commands in the Workspace
window on the left of the screen.
The user has two options for analysis with SYSTAT: using the GUI, or using the command line.
To run a command, right click in the .syc file. You then can choose to run the current line or to
run the commands from the current line to the end. To specify a specific data set to use, type
“USE FileName.extension”.
Here’s an example of running commands on the SYTAT user interface.
Figure 1: The SYSTAT user interface
3. Using the GUI in SYSTAT
Basic statistics can be found under the Analyze tab. To analyze column variables, click Analyze>Basic Statistics. To analyze row variables, click Analyze->Row Statistics. You can also use the
Analyze bar to get contingency tables, scatter plot matrices and correlation matrices, and stemand-leaf plots. To get basic graphs, use the Graph tab. Options include histograms
You can also do a regression analysis using the GUI. Click Analyze->Regression and choose
what type of regression you want to do. Options include least squares and logit regression.
SYSTAT will output summary information, including residual plots. Some of the regression
output will show up on in the Workspace window toward the left of the screen. You can tell
SYSTAT to save the residuals. Other options include bootstrapping and normality tests.
Figure 2: Using the GUI for Least Squares regression
You can also do ANOVA using the GUI. Click Analyze->Analysis of Variance.
4. Basic command lines in SYSTAT
Construct a qqplot
Plot Y*X
Sort by a variable
QPLOT varname
PLOT VarY*VarX
SORT varname
Normality test
Ttest
Bootstrap from a dataset
Summary statistics
CSTATISTICS varname/ ADTEST SWTEST
TESTING
TTEST var1 var2
USE Filename.extension
SAMPLE BOOT(nsamples,sample_size)/MEAN MEDIAN
CSTATISTICS variable1 variable2
CSTATISTICS varname
5. Linear Regression
You have more control over your model form if you use the command line for regression. For
example, to run a multiple linear regression including interaction and quadratics, you might type:
REGRESS
USE POP.syz
MODEL GRADE=AGE RACE$ GOALS$ GENDER$ AGE*GOALS$ AGE*AGE
ESTIMATE
SYSTAT will automatically produce not only the standard estimates, but also interaction plots.
To have SYSTAT choose a model using stepwise regression, you might type:
REGRESS
USE POP.syz
MODEL GRADE=AGE RACE$ GOALS$ GENDER$ AGE*GOALS$ LOOKS MONEY LOOKS*MONEY
START / FORWARD
STEP / AUTO
STOP
SYSTAT will start with the variables in the model statement, run stepwise regression, and return
the optimal model.
If you want to save the residuals when running a regression analysis, type
“SAVE RESIDS/ RESID DATA”
before the ESTIMATE statement.
6. Logistic Regression
Just add the keyword LOGIT before the MODEL statement; for example:
USE Barley.syz
LOGIT
MODEL VAR_5=CONSTANT+Y1931
ESTIMATE
SYSTAT will output the ROC curve
7. Fixed Effect ANOVA using SYSTAT
A. One-Way ANOVA
For a one-way ANOVA, you specify first the labels of the category, and then the dependent
variable you want to consider. For example, if you wanted to know whether the price of whiskey
depends on whether or not the company is a monopoly, you would type:
ANOVA
USE WHISKEY.syz
CATEGORY POLICY$
DEPEND PRICE
ESTIMATE
The output includes the interaction plot.
B. Two-Way ANOVA
The format is basically the same for a two-way ANOVA; just add an extra variable to the
CATEGORY statement. In SYSTAT, the ANOVA command automatically adds interactions to
the model and tests for them.
C. Options When Using ANOVA
Add a covariate (goes before
ESTIMATE statement)
Estimate effects
Specify type of Sum of Squares
COVARIATE varname
ESTIMATE
ESTIMATE /SS=TYPE3
8. Random Effects
As far as I can tell, to do a random effect ANOVA, you need to use the MIXED command. For
example, suppose you wanted to see if barley yield depended on variety and site, and that site
was considered a random effect. You would type:
USE BARLEY.syz
MIXED
CATEGORY VARIETY$ SITE$
MODEL Y1932=VARIETY$ + SITE$
RANDOM SITE$
ESTIMATE
9. Manipulating datasets
In some cases you may want to alter a dataset. I will give examples to illustrate how to do basic
data manipulation.
Create new variable
Drop a data point
Merge data sets
IF SMOKING < 100 THEN LET SMOKERATE$='LOW'
IF SMOKING==77 THEN DELETE
MERGE Smoke2.syz Smoke1.syz
Delete a column variable
DELETE COLUMNS=SMOKING