Abstract:This paper proposes two methods for estimating panel data models with group specific parameters when group membership is not known. The first method uses the individual level time series estimates of the parameters to form threshold variables. The problem of parameter heterogeneity is turned into estimation of a panel threshold model with an unknown threshold value. The second method modifies the K-means algorithm to perform conditional clustering. Units are clustered based on the deviations between the indivi… Show more
“…It is important, however, to remark that our approach requires a priori information on the block structure. If this is not available, then one could exploit methods from the clustering literature that allow us to determine endogenously the optimal grouping of cross-sectional units, such as the k-means algorithm (Forgy, 1965) extended to allow for covariates in the model; see, in particular, Lin and Ng (2012) and Bonhomme and Manresa (2015), and also Ando and Bai (2016). Our approach also has potential application in the area of spatial econometrics.…”
Section: The Set Of Indices Of All Non-zero Offdiagonal Elements In mentioning
confidence: 99%
“…When the grouping is not fully known a priori, we could use methods that allow us to determine endogenously the optimal grouping of cross-sectional units, by employing techniques from the clustering literature; see, e.g. Lin and Ng (2012), Bonhomme and Manresa (2015) and Ando and Bai (2016).…”
SummaryNetworks with a very large number of nodes appear in many application areas and pose challenges for traditional Gaussian graphical modelling approaches. In this paper, we focus on the estimation of a Gaussian graphical model when the dependence between variables has a block-wise structure. We propose a penalized likelihood estimation of the inverse covariance matrix, also called Graphical LASSO, applied to block averages of observations, and we derive its asymptotic properties. Monte Carlo experiments, comparing the properties of our estimator with those of the conventional Graphical LASSO, show that the proposed approach works well in the presence of block-wise dependence structure and that it is also robust to possible model misspecification. We conclude the paper with an empirical study on economic growth and convergence of 1,088 European small regions in the years 1980 to 2012. While requiring a priori information on the block structure -e.g. given by the hierarchical structure of data -our approach can be adopted for estimation and prediction using very large panel data sets. Also, it is particularly useful when there is a problem of missing values and outliers or when the focus of the analysis is on out-of-sample prediction.
“…It is important, however, to remark that our approach requires a priori information on the block structure. If this is not available, then one could exploit methods from the clustering literature that allow us to determine endogenously the optimal grouping of cross-sectional units, such as the k-means algorithm (Forgy, 1965) extended to allow for covariates in the model; see, in particular, Lin and Ng (2012) and Bonhomme and Manresa (2015), and also Ando and Bai (2016). Our approach also has potential application in the area of spatial econometrics.…”
Section: The Set Of Indices Of All Non-zero Offdiagonal Elements In mentioning
confidence: 99%
“…When the grouping is not fully known a priori, we could use methods that allow us to determine endogenously the optimal grouping of cross-sectional units, by employing techniques from the clustering literature; see, e.g. Lin and Ng (2012), Bonhomme and Manresa (2015) and Ando and Bai (2016).…”
SummaryNetworks with a very large number of nodes appear in many application areas and pose challenges for traditional Gaussian graphical modelling approaches. In this paper, we focus on the estimation of a Gaussian graphical model when the dependence between variables has a block-wise structure. We propose a penalized likelihood estimation of the inverse covariance matrix, also called Graphical LASSO, applied to block averages of observations, and we derive its asymptotic properties. Monte Carlo experiments, comparing the properties of our estimator with those of the conventional Graphical LASSO, show that the proposed approach works well in the presence of block-wise dependence structure and that it is also robust to possible model misspecification. We conclude the paper with an empirical study on economic growth and convergence of 1,088 European small regions in the years 1980 to 2012. While requiring a priori information on the block structure -e.g. given by the hierarchical structure of data -our approach can be adopted for estimation and prediction using very large panel data sets. Also, it is particularly useful when there is a problem of missing values and outliers or when the focus of the analysis is on out-of-sample prediction.
“…. , G K 0 in this parametric framework has been considered, for example, in Sarafidis and Weber (2014) and Su et al (2014) who work with penalization techniques, and in Lin and Ng (2012) who employ thresholding and k-means clustering methods.…”
Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. We investigate a nonparametric panel model with heterogeneous regression functions. In a variety of applications, it is natural to impose a group structure on the regression curves. Specifically, we may suppose that the observed individuals can be grouped into a number of classes whose members all share the same regression function. We develop a statistical procedure to estimate the unknown group structure from the observed data. Moreover, we derive the asymptotic properties of the procedure and investigate its finite sample performance by means of a simulation study and a real-data example.
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“…There are a small number of papers that study panel data models with unobserved heterogeneity when group membership is unknown. Bonhomme and Manresa (2012), Lin and Ng (2012) and Sun (2005) investigated this challenging problem. In contrast to previous models, there is a factor structure in each group.…”
Section: Introductionmentioning
confidence: 99%
“…However, there is evidence that homogeneity of the parameters is rejected (see for example Hsiao and Tahmiscioglu (1997), Lin and Ng (2012)). To deal with the presence of unobserved heterogeneity, we therefore extend the proposed model to the flexible yet parsimonious approach.…”
This paper studies panel data models with unobserved group factor structures. The group membership of each unit and the number of groups are left unspecified. The number of explanatory variables can be large. We estimate the model by minimizing the sum of least squared errors with a shrinkage penalty. The regressions coefficients can be homogeneous or group specific. The consistency and asymptotic normality of the estimator are established. We also introduce new C p -type criteria for selecting the number of groups, the numbers of group-specific common factors and relevant regressors. Monte Carlo results show that the proposed method works well. We apply the method to the study of US mutual fund returns under homogeneous regression coefficients, and the China mainland stock market under group-specific regression coefficients.
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