Here's a quick recap of the changes we've made to RATS from Version 4.0 to the present.
Version 5.00 (September, 2000)
New to version 5 are these instructions:
- CVMODEL estimates structural VAR’s.
- ECT adds error correction effects to a VAR.
- DLM works with state space models, employing Kalman filtering and smoothing.
- PFORM creates panel series from other sources
- PREGRESS performs fixed and random effects estimation.
- DENSITY computes empirical density functions.
There have been a number of significant changes to the non-linear estimation instructions.
- The method of specifying the set of free parameters has been made much more flexible: it's now possible to include full matrices, not just individual variables.
- Sets of parameters now form a new PARMSET variable. These can be combined using a simple “+” operation, allowing models to be created in pieces and combined only when estimated.
- A "genetic" method has been added for broader searches of the parameter space. Most instructions now offer a choice of methods.
- You can impose equality or inequality constraints on the parameters by adding the conditions (like b>=0 or a+b*c==1.0) to the parameter set.
- It is possible to define a VECTOR of formulas in a loop.
More than fifty new functions have been added, including functions for probability/distribution computations, matrix concatenation/extraction, series creation, and much more.
HTML and CDF (comma-delimited) have been added as options for output. Picture clauses (such as ##.##) have been added to several instructions to allow greater control over the appearance of data.
Version 4.35 (March, 1999)
Version 4.35 is a Macintosh-only release, which introduced a native PowerMac version of RATS, and incorporated all of the changes and new features introduced with versions 4.1, 4.2, and 4.3 on other platforms, as described below.
Version 4.30 (March, 1997)
Version 4.3 added the following new features:
- New instructions for building and testing neural net models.
- Built-in instruction for solving linear programming and quadratic programming problems.
- New function for solving systems of linear equations.
- For UNIX systems, it added the ability to view graphs directly on the screen (already available for desktop versions).
Version 4.20 (April, 1995)
Version 4.2 was a major update that included the introduction of the first versions of RATS written for the Windows operating system. WinRATS is available in both a 16-bit version and a faster 32-bit (Win32s) version. Other improvements in RATS 4.2 included:
- Several new instructions for writing interactive programs, including USERMENU for user-defined pull-down menus, INFOBOX and MESSAGEBOX for displaying informational dialog boxes, and SELECT for displaying pop-up selection lists.
- Many enhancements to the graphics capabilities, including:
- New GRTEXT instruction for placing text anywhere inside a graph.
- Simplified handling of two-scale graphs.
- Additional labeling options for SPGRAPH's.
- The ability to export graphs to formats such as PostScript, PIC, and HPGL directly from RATS.
- Several new functions:
- %INVNORMAL and %INVCHISQR for inverse Normal and inverse Chi-square distributions.
- %MILLS and %DMILLS for computing Mills' ratio and its derivative.
- %XDIAG, %XROW, and %XCOL for extracting the diagonal or a specific row or column from an array.
- %LEFT, %RIGHT, and %MID extract characters from LABEL variables.
- Support for reading directly from Excel files and the DRI Basic Economics (formerly Citibase) database.
Version 4.10 (March, 1994)
Improvements in Version 4.10 included:
- Several enhancements to the interface of the DOS versions, including mouse support, the ability to keep several graphs in memory at one time, the option of "buffering" output to improve performance, and more.
- Added additional data compaction options and support for reading/writing data in the DIF and DBF formats.
- Two functions: %LOGDENSITY(A,B), which returns -.5(log|A|+B'inv(A)B), and %RANGAMMA(x) which returns a random draw from a gamma distribution with shape parameter x.
Version 4.0 (April, 1992)
RATS Version 4.0 represented the most comprehensive update in the history of RATS. The program was entirely rewritten in the C programming language, many improvements were made, new features were added, and the RATS User's Manual benefited from extensive revisions. The following is a partial list of the changes in Version 4.0:
- Significant speed improvements over Version 3.1.
- New statistical features, including:
- Non-linear systems estimation.
- BOXJENK supports arbitrary lag structures (e.g., you can include terms for lags 1 and 3 without including a term for lag 2).
- The instruction FIND uses the simplex method to maximize/minimize any expression computed by any sequence of RATS instructions.
- Simplex method added to MAXIMIZE.
- MAXIMIZE can also handle a much wider range of models, including multivariate likelihood models.
- The RATS editor allows you to work with several "windows" at one time. For example, you can enter instructions in one window and have the output sent to a different window.
- Much more helpful error messages.
- Improved formatting of output.
- Simplified handling of scalar and matrix calculations
- Simplified system of data types makes programming easier, and allows "compound" data types, such as vectors of series.
- Variables names can now be up to 16 characters in length, rather than 8 characters.
- Scatter plots done as high-resolution graphics rather than character-based plots.
- Added support for C-style comment blocks using /* and */ notation.
- CALENDAR instruction allows for much wider range of frequencies, including multiple observations per day.
