D.22 SYSTAT

Approximate Cost: $999 (government/nonprofit Organization)

Source: www.systat.com

Operating System: Windows, UNIX, Macintosh

Input Structure: Data can be imported from a wide variety of data sources including but not limited to text/binary files, spreadsheets and databases. A BASIC-type language is available for extensive data management and manipulation within the program.

Overview

SYSTAT features 49 functions in the standard package library including bootstrapping and sampling, cluster analysis, linear regression, mixed regression, nonparametricStatistical test that does not depend on knowledge of the distribution of the sampled population (Unified Guidance). tests, random sampling, smoothing, spatial analysis, and time series analysis.

Add-Ins Available

SYSTAT Exact Tests extends the functionality of SYSTAT. This add-in uses an exact inference function to run statistical tests on sparse or imbalanced samples, where the usual asymptotical assumptions might produce misleading results.

A free student version called MYSTAT is also available. MYSTAT retains most of the full functionality of SYSTAT, except that only 100 variables are allowed, with no limits to the number of rows (cases).

Ease of Use and Data Import

The most common data structures in SYSTAT are rectangular (column/row) files, but triangular data files are also allowed. SYSTAT can import data import from ASCII files and from various popular formats such as Excel, dBase, SAS, and Minitab. Data files can be easily manipulated through the built-in BASIC-like language support. The user interface can be interactive (with all commonly used commands accessed through drop-down menus and dialog boxes), or command driven for more experienced users. Comprehensive online help documentation is available.

Types of Distributions

SYSTAT can be used for calculating properties of probability distributions, as well as to check whether a given data set fits a standard distribution. Some distributions and distributional tests supported in SYSTAT include beta, binomial, Cauchy, chi-square, exponential, F, gammaA gamma distribution or data set. A parametric unimodal distribution model commonly applied to groundwater data where the data set is left skewed and tied to zero. Very similar to Weibull and lognormal distributions; differences are in their tail behavior, and the gamma density has the second longest tail where its coefficient of variation is less than 1 (Unified Guidance; Gilbert 1987; Silva and Lisboa 2007)., Gompertz, Gumbel, lognormalA dataset that is not normally distributed (symmetric bell-shaped curve) but that can be transformed using a natural logarithm so that the data set can be evaluated using a normal-theory test (Unified Guidance)., logistic, negative binomial, normal, Poisson, Student’s T, uniform, and Weibull.

Visualization

SYSTAT has a comprehensive graphics library and can produce presentation-quality graphics for most of the commonly used plots. Graphs can be easily annotated and edited.

Primary Uses for Groundwater Data Analysis

SYSTAT is used for the following groundwater data analysis tasks:

• calculate summary statistics
• perform distributional tests
• calculate point estimates of population meanThe arithmetic average of a sample set that estimates the middle of a statistical distribution (Unified Guidance).
• calculate interval estimates of population mean with known and unknown varianceThe square of the standard deviation (EPA 1989); a measure of how far numbers are separated in a data set. A small variance indicates that numbers in the dataset are clustered close to the mean.
• perform sampling size of population mean
• calculate point and interval estimates of population proportion
• test hypotheses
• perform linear and nonlinear regression
• perform analysis on time-series and spatial data
• analyze nondetectsLaboratory analytical result known only to be below the method detection limit (MDL), or reporting limit (RL); see "censored data" (Unified Guidance). in data using substitution-type methods and also more advanced maximum likelihood estimator methods
• develop custom applications

Benefits

• flexible, interactive, and powerful environment for data analysis and visualization
• built-in support for a variety of statistical analyses ranging from simple to complex
• macros for performing complex analyses
• presentation-quality graphics and automated reports easily produced
• SYSTAT support staff and help through an extensive FAQ data base, as well as a knowledgeable online community for support issues

Limitations and Data Requirements

• Cost may be prohibitive.
• The program offers functions and libraries to read and process data from a variety of sources including but not limited to: ASCII files, binary files, spreadsheets, and databases.
• As long as the data format and structure is known, the data can be imported into SYSTAT. No data size limitations exist, other than hardware limitations of the computer running the software.

References

Krishnan, T. and R. Karandikar, Cranes Software International Ltd. An overview of the general-purpose SYSTAT software, with some examples. http://www.iasri.res.in/ebook/EB_SMAR/e-book_pdf%20files/Manual%20I/13-SYSTAT%20TUTORIAL.pdf

Wilkinson, L, Blank, G. and Gruber, C.G.1996. Desktop Data Analysis with SYSTAT. Englewood Cliffs, NJ: Prentice-Hall.

 

Publication Date: December 2013