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Abstract Scout

Scout 2008 Version 1.00.01

The Scout 2008 version 1.00.01 software package provides a wide variety of classical and robust statistical methods that are not typically available in other commercial software packages. A major part of Scout deals with classical, robust, and resistant univariate and multivariate outlier identification, and robust estimation methods that have been available in the statistical literature over the last three decades. Outliers in a data set represent those observations which do not follow the pattern displayed by the majority (bulk) of the data. It should be pointed out that all of the outlier identification methods are meant to identify outliers in a data set typically representing a single population. Outlier identification methods are not meant to be used on clustered data sets representing mixture data sets, especially when more than two clusters may be present in the data set. On data sets having several clusters, other methods such as cluster analysis and principal component analysis may be used. Several robust estimation and outlier identification methods that have been incorporated into Scout 2008 include: the iterative classical method, the iterative influence function (e.g., Biweight, Huber, PROP)-based M-estimates method, the multivariate trimming (MVT) method, the least median-of-squared residuals (LMS) regression method, and the minimum covariance determinant (MCD) method. Some initial choices for the iterative estimation of location and scale are also included in Scout 2008, including the orthogonalized Kettenring and Gnanadesikan (OKG) method; the median, median absolute deviation (MAD), or inter-quartile range (IQR)-based methods; and the MCD method. Scout offers classical and robust methods to estimate: the multivariate location and scale, univariate robust intervals, multiple linear regression parameters, principal components (PCs), and discriminant (Fisher, linear, and quadratic) functions (DFs). The discriminant analysis module of Scout can perform cross validation using several methods, including leave-one-out (LOO), split samples, M-fold validation, and bootstrap methods. Below detection limit observations or non-detect (ND) data are inevitable in many environmental and chemometrics applications. Scout has several univariate graphical and inferential methods that can be used on uncensored full data sets and also on left censored data sets with below detection limit (DL) observations. Specifically, Scout can be used to: compute various interval estimates, perform typical univariate goodness-of-fit (GOF) tests, and perform single and two-sample hypothesis tests on uncensored data sets and left-censored data sets with non-detect observations. Classical univariate statistical inference methods (e.g., intervals and hypothesis testing) in Scout 2008 can also handle data sets with below detection limit observations. In Scout 2008, emphasis is given to graphical displays of multivariate data sets. Both two-dimensional and three-dimensional graphs can be generated using Scout. The classical and robust methods listed above are supplemented with formal multivariate classical and robust graphical displays, including the quantile-quantile (Q-Q) plots of the Mahalanobis distances (MDs), index plots of the MDs, distance-distance (D-D) plots, scatter plots of raw data, PC scores, and DF scores with prediction or tolerance ellipsoids superimposed on the respective scatter plots. Those graphical displays can be drawn using the critical values of the MDs obtained using the exact scaled beta distribution of the MDs or an approximate chi-square distribution of the MDs. Some graphical classical and robust methods comparison tools are also available in Scout so that one can graphically compare the performances of those methods. Scout can be used to display tolerance ellipsoids or prediction ellipsoids for the various outlier identification methods on the same graph and to display robust regression lines for the various regression methods on the same graph. Scout 2008 also offers some GOF test statistics to assess multivariate normality. Several GOF test statistics, including the multivariate kurtosis, the skewness, and the correlation coefficient between the ordered MDs and the scaled beta (or chi-square) distribution quantiles, are displayed on a Q-Q plot of the MDs. The associated critical values of those GOF test statistics (obtained via extensive simulation experiments) are also displayed on the graphical displays of the Q-Q plots of the MDs. Two standalone software packages, ProUCL 4.00.03 and ParallAX, have also been incorporated into Scout 2008. ProUCL 4.00.03 is a statistical software package developed to address environmental applications, whereas the ParallAX software offers graphical and classification tools to analyze multivariate data using the parallel coordinates.

Installing Scout 2008 Version 1.00.01

Minimum Hardware Requirements

Software Requirements

Scout has been developed in the Microsoft .NET Framework using the C# programming language. As such, to properly run Scout, the computer using the program must have version 1.1 of the .NET Framework pre-installed. The downloadable .NET files can be found at one of the following two Web sites:

The first Web site lists all of the downloadable .NET Framework files, while the second Web site provides information about the specific file(s) needed to run Scout. Download times are estimated at 57 minutes for a dial-up connection (56K), and 13 minutes on a DSL/Cable connection (256K).

Scout 2008 v. 1.00.01 Installation Instructions from the Web Site

  1. Open Windows Explorer and create a new directory called Scout 2008 v. 1.00.01.

  2. Download (save) the Scout 2008 v. 1.00.01 files from the web site to the Scout 2008 v. 1.00.01 directory.

  3. Using Windows Explorer, right click on the Scout 2008 v. 1.00.01 main directory and make sure that the read-only attribute is off.

  4. Using Windows Explorer, create a shortcut (optional) by right-clicking on the file, Scout.exe (application), in the Scout directory; left click on “Send To” and left click on “Desktop (create shortcut)” to create a shortcut icon the desktop (optional: rename to Scout 2008 v. 1.00.01).

  5. Using Windows Explorer, start Scout 2008 v. 1.00.01 by left double-clicking on the file, Scout.exe (application), in the Scout directory, or by left double-clicking on the Scout shortcut icon on the desktop, or by using the RUN command from the Start Menu to locate and run Scout.exe.

  6. Try to open an example file in the Scout sub-directory, Data. If the file does not open, be sure that the read-only attribute is off (right-click on the Data sub-directory).

  7. If the computer does not have .NET Framework 1.1 (it must be this version) installed (either a pre-2002 Windows operating system or a late version of Windows XP), then it will be necessary for the end user to download it from Microsoft. A Google search for “NET Framework 1.1” will yield several download locations, or use the web sites provided above.

  8. The statistical software package, Scout 2008 Version 1.00.01, and the Scout Resources (guides, instructions, and sample data), may be downloaded by double-clicking on the on the site below:
    Scout 2008 Version 1.00.01 (zip file, 190 MB)

  9. Other documentation that may be downloaded from this site may be downloaded by double-clicking on the on the site below (this information is included in the Scout Resources folder in the above download site):

    Scout 2008 Version 1.00.01

    Quick Overview Scout 2008
    (PDF, 20 pp., 1.15 MB, About PDF)
    Quick Overview Scout 2008 (Microsoft Word, 20 pp., 147 KB)

    User Guide Part 1 (PDF, 244 pp., 8.3 MB, About PDF)
    User Guide Part 1 (Microsoft Word, 244 pp., 11.82 MB)

    User Guide Part 2
    (PDF, 132 pp., 6.7 MB, About PDF)
    User Guide Part 2 (Microsoft Word, 132 pp., 8.72 MB)

    User Guide Part 3 (PDF, 124 pp., 4.89 MB, About PDF)
    User Guide Part 3 (Microsoft Word, 124 pp., 147 KB)

    User Guide Part 4 (includes Bibliography)
    (PDF, 218 pp., 11.48 MB, About PDF)
    User Guide Part 4 (includes Bibliography) (Microsoft Word, 218 pp., 7.99 KB)

The Scout 2008 software and the Scout 2008 User Guide are “works in progress.” Any significant updates or versions will be posted on this web site. We have not been able to complete a Scout 2008 Technical Guide at the time of this posting (it will be posted on this web site when completed). To compensate, we include some guides, guidance documents, a bibliography (in the User Guide), and some reference articles in the Scout Resources folder that should prove helpful for technical background.

Contact Information

John H. Zimmerman (Acting Branch Chief)
Res. Physical Scientist
(702) 798-2385
(702) 798-2107 fax
zimmerman.johnh@epa.gov

Installation Instructions (for Scout older versions -- DOS v. 2.0 and WinScout)

Environmental Sciences | Research & Development
National Exposure Research Laboratory
Send questions or comments to the ESD Info Desk (contractor operated)
(Library-lv@epa.gov)


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