Greetings My name is Camila Villegas, I write to you about a fault that I found in the rugarch package and that I would like to discuss with you. For my master's research, I conducted simulations with the rugarch package to evaluate its operation with a TGARCH model (1,1). First I analyzed the convergence of the estimated parameters and they presented no problems. plus the mean square error decreased as the sample size increased. The validation of the modeling results (obtained by the "ugarchfit" function) I carried out by analyzing the residues generated by the "residuals" function. The simulated residues originally had zero mean and variance one, however, in the 10,000 simulations that I developed, the values of the variances of the residues generated by the "ugarchfit" function were significantly different from one. On the contrary, when calculating the residues "manually" and only using the parameters estimated by the package, we obtained means close to zero and variances close to one. With this last point, I observed a flaw in the residues delivered by the rugarch package for a TGARCH process (1,1), since they do not have the same variance with which they were simulated. Thanking your observations, Kind Regards. Camila Villegas Orellana
Problems with rugarch package
2 messages · Camila Villegas, Alexios Ghalanos
Hi Camila, Can you provide some reproducible code to help us investigate and debug this issue. It is hard to do so from the description provided. Thanks, Alexios
On Feb 4, 2020, at 10:00 AM, Camila Villegas <camila.villegas.orellana at gmail.com> wrote: ?Greetings My name is Camila Villegas, I write to you about a fault that I found in the rugarch package and that I would like to discuss with you. For my master's research, I conducted simulations with the rugarch package to evaluate its operation with a TGARCH model (1,1). First I analyzed the convergence of the estimated parameters and they presented no problems. plus the mean square error decreased as the sample size increased. The validation of the modeling results (obtained by the "ugarchfit" function) I carried out by analyzing the residues generated by the "residuals" function. The simulated residues originally had zero mean and variance one, however, in the 10,000 simulations that I developed, the values of the variances of the residues generated by the "ugarchfit" function were significantly different from one. On the contrary, when calculating the residues "manually" and only using the parameters estimated by the package, we obtained means close to zero and variances close to one. With this last point, I observed a flaw in the residues delivered by the rugarch package for a TGARCH process (1,1), since they do not have the same variance with which they were simulated. Thanking your observations, Kind Regards. Camila Villegas Orellana [[alternative HTML version deleted]]
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