#

**NAME:**
**
Statistics and Probability Distributions
v. 1.02 ** (Click Name to Download)

**AKA:** stats_dist.avx

**Last Modified:** October 12, 2003

**TOPICS:** Statistics, Distributions, t, F,
logistic, normal, skewness, kurtosis, binomial, probability, critical,
Poisson, chi-square, cumulative

**AUTHOR:** Jeff
Jenness

GIS Analysis and Application Design

Jenness Enterprises,
www.jennessent.com

jeffj@jennessent.com

**DESCRIPTION:** This extension gives you the
ability to calculate a wider range of summary statistical data than the
basic set provided by ESRI, and also the power to generate probability
values and critical values from a wide range of statistical
distributions.

**Summary Statistics:** From any numeric field in a
table, this function will calculate the Mean, Standard Error of the
Mean, Confidence Intervals, Minimum, 1st Quartile, Median, 3rd Quartile,
Maximum, Variance, Standard Deviation, Average Absolute Deviation,
Skewness (normal and Fisher’s G1), Kurtosis (normal and Fisher’s G2),
Number of Records, Number of Null Values, and Total Sum.

**Probability Calculators:** This function will
allow you to calculate the probability, cumulative probability and
inverse probability (i.e. given a cumulative probability, calculate the
corresponding critical value) of a wide range of statistical
distributions, including the Beta, Binomial, Cauchy, Chi-Square,
Exponential, F, Logistic, LogNormal, Normal, Poisson, Student’s T and
Weibull distributions. This function is available as a general
calculator that remains open until you are finished with it, or as a
Table tool that performs the calculations on all selected records in a
table.

**REQUIRES:** This extension requires that the
Dialog Designer DLL file be available in your ArcView/BIN32 directory
(or $AVBIN/avdlog.dll), which it almost certainly is if you're running
AV3.1 or higher. You don't have to load the Dialog Designer; it only has
to be available. If you are running ArcView 3.0a, you can download the
appropriate files for free from ESRI, at:

http://support.esri.com/index.cfm?fa=downloads.patchesServicePacks.viewPatch&PID=25&MetaID=483

**UPDATES****: **The
1.01 update fixes a typo in the "Average Absolute Deviation" calculation
which caused it not to be divided by N, and gives more programming
functions to Avenue developers. The 1.02 update adds "Range" to
the list of calculated statistics. The March 5 update makes no
changes to the extension, but rather corrects some errors in the manual
pertaining to generating summary statistics with Avenue. The
October 12 update corrects some typos in the manual on formulas for the
PDF and IDF Normal and LogNormal functions.

**GENERAL INSTRUCTIONS: **

1: Begin by placing the “stats_dist.avx” file into the
ArcView extensions directory (../../Av_gis30/Arcview/ext32/).

2: After starting ArcView, load the extension by
clicking on File --> Extensions… , scrolling down through the list of
available extensions, and then clicking on the checkbox next to the
extension called “Statistics and Distributions”

**For Further Information on Tools and Distribution
Functions****:**

Summary Statistics |
Probability
Calculators | References

Calculating
Summary Statistics with Avenue

**Discussion of Distribution Functions:**

Probability Density Functions | Cumulative Distribution Functions |
Quantile Functions

Download
Statistics Extension Manual
(Adobe PDF, version 5 or later)

Enjoy! Please contact the author if you have problems or find bugs.

Jeff Jenness
jeffj@jennessent.com

3020 N. Schevene Blvd.

Flagstaff, AZ 86004

USA

Please visit *Jenness Enterprises*
ArcView
Extensions site for more ArcView Extensions and other software by
the author. We also offer customized ArcView-based
GIS consultation
services to help you meet your specific data analysis and application
development needs.