Announcing the Release of Oxmetricstm5
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OxMetrics www.oxmetrics.net www.timberlake.co.uk www.timberlake-consultancy.com OxMetrics news AUGUST 2007 ISSUE 7 NEW MODULES NEW RELEASES FAQS USERS VIEWS COURSES AND SEMINARS Announcing the release of OxMetricsTM5 OxMetrics™ is a modular software system state space forms: from a simple time-invariant In OxMetrics™ 5, all the modules of OxMetrics™ providing an integrated solution for the model to a complicated multivariate time- Enterprise Edition have been upgraded. econometric analysis of time series, forecasting, varying model. Functions are provided to put The details of new features are described below: financial econometric modelling, or statistical standard models such as ARIMA, Unobserved analysis of cross-section and panel data. The components, regressions and cubic spline New feature: Autometrics™ OxMetrics modules are: models into state space form. Basic functions by Jurgen. A. Doornik • Ox™ Professional is a powerful matrix are available for filtering, moment smoothing language, which is complemented by a and simulation smoothing. Ready-to-use 1 Autometrics comprehensive statistical library. Among the functions are provided for standard tasks such special features of Ox are its speed, well- as likelihood evaluation, forecasting and signal 1.1 Introduction designed syntax and editor, and graphical extraction. SsfPack can be easily used for With their publication in 1999, 1 Hoover and Perez facilities. Ox can read and write many data implementing, fitting and analysing Gaussian revisited the earlier experiments of Lovell, and formats, including spreadsheets; Ox can run models relevant to many areas of showed that an automated general-to-specific most econometric GAUSS programs. Ox™ econometrics and statistics. Furthermore it model selection (Gets) algorithm can work Packages extend the functionality of Ox in provides all relevant tools for the treatment of successfully. This contrasts with the results of various ways. Once installed, they become an non-Gaussian and nonlinear state space Lovell, who only considered simplistic methods integrated part of Ox. Some packages just add models. In particular, tools are available to such as forward selection, showing that these a few useful functions, whereas others offer an implement simulation based estimation can fail badly. extensive econometric or statistical technique methods such as importance sampling and which can also be used interactively using Ox Markov chain Monte Carlo (MCMC) methods The success of automated Gets created Professional. Most of these packages are FREE (not yet released). renewed interest in computer-based algorithms. of charge (see www.doornik.com for full list of • TSP/GiveWin™ by TSP International (founded In particular, Hendry and Krolzig extended available packages) in 1982 by Bronwyn H. Hall) is an econometric the algorithm of Hoover–Perez and developed • PcGive™ aims to give an operational and software package, with convenient input of PcGets, a user-friendly computer program structured approach to econometric modelling commands and data, all the standard aimed at the empirical modeller. PcGets was using the most sophisticated yet user-friendly estimation methods (including non-linear), part of GiveWin 2. software. The accompanying books transcend forecasting, and a flexible language for Autometrics can be seen as the third generation, the old ideas of `textbooks' and `computer programming your own estimators. The taking many features of the earlier manuals' by linking the learning of econometric philosophy behind TSP is that of a command- implementations, but also differing in some methods and concepts to the outcomes driven language tailored to econometric aspects. Starting with OxMetrics 5, Autometrics achieved when they are applied. The problems, whatever the platform used. For is part of PcGive - now automatic model econometric techniques of PcGive include: those working in a Windows environment, TSP selection can be activated with as little as a VAR, cointegration, simultaneous equations can be installed as a module of OxMetrics - single click. models, ARFIMA, logit, probit, GARCH TSP/GiveWin. This eases the use of the modelling, static and dynamic panel data command-line environment by providing 1.2 An example models, X12ARIMA, and more. context sensitive help, syntax highlighting, and To illustrate the use of Autometrics, we use the • STAMP™ is designed to model and forecast a dialog-driven command builder. tutorial data set of PcGive, taking 12 lags of all time series, based on structural time series variables. models. These models use advanced Four of these modules have been grouped in a The initial model is formulated in PcGive as any techniques, such as Kalman filtering, but are single product OxMetrics™ Enterprise Edition. other dynamic model: set up so as to be easy to use -- at the most OxMetrics™ Enterprise Edition is a single basic level all that is required is some product that includes and integrates all the appreciation of the concepts of trend, seasonal important components for theoretical and and irregular. The hard work is done by the empirical research in econometrics, time series program, leaving the user free to concentrate analysis and forecasting, applied economics and on formulating models, then using them to financial time series: Ox Professional, PcGive, make forecasts G@RCH, and STAMP. • G@RCH ™ is dedicated to the estimation and OxMetrics™ is distributed and published by forecasting of ARCH and GARCH-type models. Timberlake Consultants Ltd G@RCH provides a user-friendly interface (with (www.timberlake.co.uk). Timberlake Consultants rolling menus) as well as some graphical Limited, with head office in the U.K., is features. celebrating its 25th anniversary in 2007. The • SsfPack™ provides Ox with additional facilities Company has a growing number of offices and when carrying out computations involving the agents worldwide, including Brazil, Japan, statistical analysis of univariate and Poland, Portugal, Spain and the USA. We also multivariate models in state space form. have partners in other countries to help with the SsfPack allows for a full range of different distribution of the OxMetrics software. This general unrestricted model, or GUM, is the regression can sometimes work (experiment 7 3 Comparison with PcGets starting point for the automatic model selection has high t-values), but also fail badly compared to procedure. The model settings dialog now has an Autometrics. Autometrics and PcGets have much in common: Autometrics section: both are algorithms for automatic model 1 Hoover, K.D. & Perez, S.J. (1999), Econometrics Journal, 2, selection within the general-to-specific 167–191. Lovell, M. C. (1983), Review of Economics and Statistics, 65, 1–12. framework. However, there are some important Hendry, D. F. & Krolzig, H.-M. (1999) Econometrics Journal, 2, differences too: 202–219. • Strategy PcGets has two strategies: Liberal and 2 More variables than observations Conservative. These correspond to 5% and 1% with carefully calibrated presearches. One exciting development is that Autometrics can Expert mode allows for different settings, but handle more variables than observations. looses the calibration between the various The main choice is the significance level of the Traditionally, this is considered infeasible — search components. reduction, kept at 5%. indeed, up to now PcGive would refuse to In Autometrics, the nominal size of the Autometrics finds four terminal models, and estimate such an equation. However, recently reduction is specified directly, with the chooses: David Hendry, Søren Johansen and Carlos Santos remainder adjusted accordingly. considered adding a dummy variable for each Coefficient Std.Error t-value observation. They study the theoretical • Presearch CONS_1 0.821298 0.03277 25.1 properties, and give a feasible algorithm (which Autometrics relies much less on presearch. CONS_4 0.145121 0.05118 2.84 differs from the one Autometrics uses). CONS_5 -0.119526 0.04076 -2.93 Simulation experiments show almost the same INC 0.519890 0.02719 19.1 Now, when Autometrics is switched on, PcGive operating characteristics with and without INC_1 -0.293790 0.03266 -9.00 will switch to blocking mode when there are presearch. INFLAT -1.00600 0.09926 -10.1 insufficient observations (usually k > 0.8T ). This • Path search INFLAT_8 0.390943 0.1237 3.16 happens automatically, whether such a model OUTPUT_12 -0.0557579 0.01388 -4.02 Autometrics does not implement the multiple- was formulated on purpose or by accident! path search. This was introduced by Hoover– The entries with lag 2 or more are not in the DGP. Some caution though: the blocking algorithm Perez to mimic the human modeller. However, However, the DGP also has a break, which is not does not fit the Gets framework anymore, and the objective of using the computer is to allowed for in the model. complex interactions may be missed. improve on that where possible. With presearch lag reduction switched off, To illustrate the procedure, we added 20 white Autometrics uses a tree search, systematically PcGive finds six terminal models. But the one noise variables to the dataset, labelled z. traversing the whole model space. with the lowest Schwarz criterion is the same as The GUM is: Several strategies are used to speed this up, before. One of the objectives of Autometrics was resulting in more frequent use of F-tests rather to reduce the dependence on presearch. than t-tests, as well as cutting off irrelevant paths. Never is the same model