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:: Wessa.net - Web-enabled scientific services & applications :: |
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All rights reserved. The non-commercial (academic) use of this software is free of charge. The only thing that is asked in return is to cite this software when results are used in publications.
Web-Enabled Scientific Services & Applications
(C)opyright 2002-2010 written by Prof. dr. P. Wessa
Server date: September 11, 2010, 2:55 am
This complicated online software application is the result of our continuous Research & Development efforts in the field of multidisciplinary Time Series Analysis in general and Financial Econometrics in particular. At the moment we cannot offer a complete reference manual due to the fact that the software is rapidly evolving, offering many new features and methods in a short period of time. A few simple examples however can be found here. Below you can find an incomplete list of the features that are currently available in this module. Please, feel free to drop us a line if you have any suggestions or questions.
| Example of Box-Jenkins Time Series Analysis |
| 1 | select Browser or Excel in the first selection box (this specifies how the output is displayed) |
| 2 | select Airline in the [data series] selection box |
| 3 | select Spectrum/(P)ACF in the [command] selection box |
| 4 | set L = 0 (this is the 'lambda' value of the Box-Cox transformation) |
| 5 | set d = 1 (this is the non-seasonal differencing order) |
| 6 | set D = 1 (this is the seasonal differencing order) |
| 7 | set s = 12 (default value; this is the number of periods per year = seasonality) |
| 8 | set K = 37 (this is the number of time lags to be computed) |
| 9 | click the lower Execute button |
| 10 | Now we can identify the ARMA model of the stationary time series. In this case we identify a non-seasonal MA(1) and a seasonal SMA(1) model. Hence, q=1 and Q=1. |
| General Commands |
| Edit data | Edit time series data (in textbox). |
| Meta data | Edit the meta data about the time series. |
| Specific Diagnostic Tools in Box-Jenkins ARIMA modeling |
| VRM | Compute Variance Reduction Matrix. |
| SMP | Compute Standard Deviation-Mean Plot. |
| ACF | Compute Auto Correlation Function for K timelags. |
| ACF(d,D) | Compute Auto Correlation Function for various degrees of non-seasonal differencing (d) and seasonal differencing (D). |
| PACF | Compute Partial Auto Correlation Function for K timelags. |
| Spectrum | Compute Normalized Cumulative Periodogram and Spectrum. |
| Spectrum/(P)ACF | Compute the Auto Correlation Function, the Partial Auto Correlation Function, and the Normalized Cumulative Periodogram (Spectrum) for the time series under investigation. |
| Estimate | Compute (estimate) all ARMA parameters (Full Information Maximum Likelihood Estimation). |
| Forecast | Compute the Univariate Stochastic ARMA Forecast (Ceteris Paribus Forecast). |
| Simulation of Profit Densities |
| PDensity | Compute the Profit Density of profits based upon a distribution-free simulation with 10*K = number of simulated profits, and M = 0 (default) for rejection of negative prices ('Metropolis' step). Note: do not set the number of K above 100 (= 1000 simulated profits) to save system resources. |
| General Descriptive Statistics |
| Timeplot | Compute basic statistics and chart of time series values. |
| Histogram | Compute histogram of time series values. |
| Rootogram | Compute suspended rootogram display of time series values. |
| Central Tendency | Compute various types of averages. |
| Concentration | Compute various types of concentration measures. |
| Moments | Compute centered and uncentered moments. |
| Skewness/Kurtosis | Compute and test various measures of Skewness and Kurtosis (small and large sample tests against normal distribution). |
| Quartiles | Compute Quartiles based upon 8 different definitions. |
| Percentiles | Compute Percentiles based upon 8 different definitions. |
| Variability | Compute various measures of Variability for the time series. |
| Series types |
| original series | Apply analysis to the original (raw) time series after Box-Cox transform and differencing. |
| residual series | Apply analysis to the residuals of the ARMA model (void if no ARMA model has been estimated). |
| squared residuals | Apply analysis to the squared residuals of the ARMA model (void if no ARMA model has been estimated). |
| interpolation | Apply analysis to the interpolation forecast of the ARIMA model (void if no ARIMA model has been estimated). |
| stationary variance | Apply analysis to W[t] = (lnY[t] - lnY[t-1]) (lnY[t] - lnY[t-1]) (this is used in the analysis of financial time series). |
| stationary range | Apply analysis to W[t] = |lnY[t] - lnY[t-1]| (this is used in the analysis of financial time series). |
| PD Buy and Hold | Apply analysis to the simulated Profit Density (PD) for the Buy&Hold strategy. Note: this assumes that the simulations have been previously computed. |
| PD Filter-rule | Apply analysis to the simulated Profit Density (PD) for the Filter-rule strategy. Note: this assumes that the simulations have been previously computed. |
| PD BH - Filter | Apply analysis to the simulated difference in Profit Density (PD): Buy&Hold profits - Filter-rule profits. Note: this assumes that the simulations have been previously computed. |
| Parameter list |
| L | Lambda: parameter of the Box-Cox transformation function. |
| d | Degree of non-seasonal differencing. |
| D | Degree of seasonal differencing. |
| s | Seasonality: number of observations per year. |
| K | Number of timelags to be used in computations (number of iterations in simulations = 10 K). |
| p | Degree of non-seasonal AR(p) polynomial. |
| q | Degree of non-seasonal MA(q) polynomial. |
| P | Degree of seasonal SAR(P) polynomial. |
| Q | Degree of seasonal SMA(Q) polynomial. |
| M | set M = 1 to include a constant term (M = 0 otherwise) |
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To cite Wessa.net in publications use: Wessa, P. (2010), Free Statistics Software, Office for Research Development and Education, version 1.1.23-r6, URL http://www.wessa.net/
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Software Version : 1.1.23-r6 Algorithms & Software : Patrick Wessa, PhD Facilities : Resa R&D - Office for Research, Development, and Education Server : www.wessa.net
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