It’s been a while since we updated our blog – that’s because we have been working on a new version of EasyFit planned to be released later in October 2008. Below is a quick summary of new features in EasyFit.
(Note: The price for the new version is likely to increase, but since all licenses come with one year of free updates, you can still order EasyFit at the current price this month and upgrade to the upcoming new version for free.)
New Probability Distributions
EasyFit will include 15 new distributions:
The Burr (Singh-Maddala), Dagum (Inverse Burr), Pareto Type II (Lomax), and Log-Gamma distributions are mainly used in economics and actuarial science. We have had numerous requests for these models from some of our customers – actuaries and finance industry professionals.
The Generalized Gamma distribution is an advanced 4-parameter model including the Gamma, Weibull, and Half-Normal distributions as special cases.
The Pearson Type V (Inverse Gamma) and Pearson Type VI (Beta Prime) distributions are a part of the Pearson family of distributions often used in financial applications.
The Levy distribution is one of the few distributions that are stable and that have probability density functions that are analytically expressible, the others being the Normal distribution and the Cauchy distribution.
The Log-Pearson III (often referred to as “LP3”) distribution is the standard model recommended by the U.S. Water Resources Council for use by all U.S. Government agencies for flood frequency analysis.
The Nakagami (Nakagami-m) and Rice (Nakagami-n) distributions are used in communications theory to model signal fading under specific conditions.
The Kumaraswamy distribution is used in electrical, civil, mechanical, and financial engineering applications dealing with variables that are lower and upper bounded.
Some other new models include the Hyperbolic Secant, Error (Exponential Power), and Reciprocal distributions.
New Excel Functions
In EasyFit 4.0, we added the ability to analyze probability data in Excel, which has proven to be quite a useful feature. EasyFit 5.0 (Professional Edition) extends this functionality by introducing several new functions making it even easier to use distributions in your worksheet models.
The DistFit function allows to fit a specified distribution to your data and display the resulting model right in a worksheet. This function can be useful if you already know the underlying distribution (e.g. the Normal model) and only need to estimate the distribution parameters. The return value of this function can be supplied to several other new functions such as DistPdf, DistCdf, DistRand etc. For example, specifying
=DistCdf(DistFit(“Normal”; B1:B100); 2)
in a worksheet will fit the Normal distribution to the data in cells B1:B100, and then evaluate the CDF of the resulting Normal distribution at x=2.