D.10 MINITAB

Approximate Cost: $1395 single-user license, $2940 for 5-user multi-user license

Source: www.minitab.com/en-US/default.aspx

Current Version: 16

Operating System Needs: XP, Vista, Windows 7, Windows 8

Input Structure: Similar to Excel spreadsheet (values for variables entered in columns).

Overview

Minitab was primarily designed for the evaluating manufacturing and service quality data rather than environmental data but is used across many industries.

Add-Ins Available 

Many freeware macros are available (including some that are useful for censored dataValues that are reported as nondetect. Values known only to be below a threshold value such as the method detection limit or analytical reporting limit (Helsel 2005). and environmental applications). Several are posted at the following websites:

• http://www.practicalstats.com
• http://www.minitab.com

Ease of Use and Data Import

Some operations (such as, generation of statistical plots and descriptive statistics) can be done with little or no training. This software contains an extensive Help menu, tutorials, sample data sets, and an Assistant menu to help select appropriate statistical procedures. It is relatively simple to import data from sources such as Excel, but environmental data with flags or nonnumerical characters can be interpreted as text and must be manually converted to numerical values (for instance, by separating or deleting the non-numeric characters). You can assign formulas to columns to automatically perform calculations. Data appear in spreadsheets that can be readily manipulated including merged, sorted, and segregated data. Graphs readily update when spreadsheet data are revised. Results are readily output to PowerPoint and MS Word.

Types of Distributions

Data can be fit to normal, 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)., and Poisson distributions. The program generates random data and outputs probability densities, cumulative probabilities, and inverse cumulative probabilities for many distributions (such as normal, lognormal, chi square, 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)., beta, exponential, F-distribution, and Poisson).

Visualization

The program's powerful, simple, and versatile graphic capability includes scatter plots, box plots, pie charts, histograms, individual value plots, and various 3-D plots. The software is useful for exploratory data analysis (EDA)An approach for initial data evaluation using graphical methods to open-mindedly explore the underlying structure and model of a dataset to aid in selection of the best statistical methods. Typical techniques are box plots, time series plots, histograms, and scatter plots (Tukey 1977; NIST/SEMATECH 2012; Unified Guidance). and generating reports.

Primary Uses for Groundwater Data Analysis

This package can be used for groundwater applications for graphing capabilities for EDA, one-sample and multi-sample parametricA statistical test that depends upon or assumes observations from a particular probability distribution or distributions (Unified Guidance). and nonparametricStatistical test that does not depend on knowledge of the distribution of the sampled population (Unified Guidance). hypothesis tests, time series evaluations, and control charts.

Benefits

• Basic functions are simple to use.
• The program offers clear and extensive help system.
• The cost is moderate (about $1,400; periodic updates cost about $600).
• Programming language and free macros are available to expand the software’s capability.

Limitations and Data Requirements

• Not designed for environmental applications
• Lack of as is capability for some common environmental statistical applications (such as prediction intervals, outlier tests, Theil-Sen lines, and user-friendly menus for left-censored data).

 

Publication Date: December 2013