Distribution Analyzer - Shareware software for normal tolerance intervals, variables sampling plans, testing normality and transformations.

Distribution Analyzer Software

Version 1.2 for Windows 95, 98, 2000, XP and Vista.

What is Distribution Analyzer?

Distribution Analyzer is a shareware software package for identifying a distribution that best fits a set of data and for estimating expected ranges for future values. It provides a means of performing Normal Tolerance Intervals (K-intervals) and Variables Sampling Plans on data that does not fit the normal distribution. The analysis performed includes:

Selection of Best Fit Distribution and Estimation of Parameters
Test of Whether Selected Distribution Adequately Fits the Data
Determination of a Transformation (Function) That Can be Applied to Data so that Transformed Data Fits the Normal Distribution
Construction of Tolerance Intervals Including a Specified Percentage of the Future Values (Normal Tolerance Interval)
Confidence Statements for Percentage of Future Values in Spec (Variables Sampling Plan)

Take an example of break force values show below. There is a lower spec limit of 4 pounds:

Data

An initial analysis of the data is shown below. By default, the normal distribution is assumed. The best fit normal distribution is shown in blue along with a histogram of the data. The Test of Fit indicates the normal distribution does does not adequately fit this set of data.

Clicking the Find Best Distribution button, identifies the Largest Extreme Value family of distributions as the best fit. The analysis for this distribution is shown below. The Test of Fit passes, so the Largest Extreme Value Distribution adequately fits the fit and can be used as the basis of further analysis.

Having passed the Test of Fit, ranges for future values are provided. First is the Tolerance Interval:

"With 95% confidence more than 99% of the values are above 5.07."

This is akin to the Normal Tolerance Interval or K-Interval but does not assume normality.

The second is relative to the spec limits:

"With 95% confidence less than 0.0031% of the values are out of spec."

This is akin to a variables sampling plan but does not assume normality.

Capabilities

Can quickly find the distribution that best fits the data
Includes the following basic distributions:
- Beta distribution
- Exponential and Negative Exponential distributions
- Largest Extreme Value family:
  - Fréchet distribution
  - Largest Extreme Value distribution
  - Negative Weibull distribution
- Smallest Extreme Value family:
  - Weibull distribution
  - Smallest Extreme Value distribution
  - Negative Fréchet distribution
- Gamma and Negative Gamma distributions
- Johnson Family of distributions
- Logistic family
  - Logisitc distribution
  - Loglogistic and Negative Loglogistic distributions
- Lognormal and Negative Lognormal distributions
- Normal distribution
- Pearson Family of distributions
- Uniform distribution
The above distributions include, as special cases, Chi-Square, Erlangian, Fisk, Log Exponential.
In addition, log-distributions are included for all the above distributions (log-Beta, log-Weibull, ...)
Fit Distributions Using Methods of Moments and Maximum Likelihood (using restrictions that ensure data and spec limits are within the range of bounded distributions).
Test whether distribution adequately fits the data
Generate tolerance interval for future values and confidence interval for percentage of future values in spec.
Generate random values for all the above distributions
Display Skewness-Kurtosis plots to understand relationships between distributions
Calculate probabilities and percentiles of the above distributions

Advantages

Simple to use. Novice users can just enter the data and click on at most 3 buttons. You don't have to be familiar with all the distributions.
You don't have to know Greek. All distributions are represented by their moments (average, standard deviation, skewness, ...). It is easy to compare distributions and generate random numbers from different distributions with the same mean, standard deviation, skewness, etc.
Complete control. Advanced users can specify distributions to use, specify bounds and parameters of the distribution. You can see the parameters of the distribution as moments or in Greek form.
Capabilities not found anywhere else
- Confidence statements relative to the percent in spec
- Wider range of distributions than any other package
- Handles bounded distributions and bounds on data to ensure meaningful results (the spec limits are always within the range of the distribution).

Download Software - 30 Day Free Trial

Distribution Analyzer is a shareware program. A full version of the software can be downloaded for a 30-day free trial. After 30 days, if you want to continue using the software, you must register it at a cost of US$275 ($297.00 for residents of Illinois). Registration entitles you to free upgrades for 1 year.

Self-Extracting File: (3,078 K)

Click the above button to download a self-extracting file. The file da12.exe will be downloaded. Executing this file will install the software on your system. This is the easiest way to download and install the software on your system.

ZIP File: (3,051 K)

Click the above button to download a ZIP file. The file da12.zip will be downloaded. You must unzip the files contained in the ZIP file into a temporary directory and then run the program setup.exe. You must have your own software for unzipping the file.

User Manual: (1,179 K)

Click the above button to download the user manual in pdf format. The user manual file da12man.pdf is also copied onto your system as part of the installation process using the two files above. It does not need to be downloaded separately. You must have a copy of the free Adobe Acrobat Reader® to view the file.

Distribution Analyzer runs under Windows 95, 98, 2000, XP and Vista. It can be easily uninstalled. It requires 3 MB of hard disk space.

Registering Software

To continue using the software after the 30-day trial period, you must register your copy of the software at a cost of US$275 ($297.00 for residents of Illinois). You can register the software using our secure server by clicking the above button. Otherwise you can register by Fax or mail using the following registration form. Also available are discounts for multiple users and site licenses.

Further Information:

General: