Search results for "error"
showing 10 items of 1643 documents
Testing Multi-Sensors Time Series of Lai Estimates to Monitor Rice Phenology: Preliminary Results
2018
Timely and accurate information on crop growth and seasonal dynamics are increasingly needed to develop monitoring systems aimed to detect seasonal anomalies, support site specific management and estimate crop yield at the end of the season. In particular, frequent decametric information nowadays being provided exploiting the new generation of Earth Observation (EO) platforms are fundamental for farm level monitoring. This study presents an analysis aimed at fully exploiting dense time series of EO data derived from the combined use of ESA Sentinel-2A and NASA Landsat-7/8 imageries for crop phenological monitoring. Decametric Leaf Area Index (LAI) maps were generated for the year 2016 by in…
Improvements in land surface temperature retrieval from the Landsat series thermal band using water vapor and air temperature
2009
[1] Land surface temperature (LST) is involved in many land surface processes such as evapotranspiration, net radiation, or air temperature modeling. In this paper we present an improved methodology to retrieve LST from Landsat 4 TM, Landsat 5 TM, and Landsat 7 ETM+ using four atmospheric databases covering different water vapor ranges (from 0 to 8 g cm−2) to build the LST retrieval models and using both water vapor and air temperature as input variables. We also compare this with LST retrievals using only water vapor or only air temperature, as well as with an existing LST retrieval algorithm. In order to validate the results, we have selected 77 Landsat images taken between 2002 and 2006 …
Seismic behavior of exterior RC beam-column joints without code-specified ties in the joint core
2021
Abstract Beam-column joint design for reinforced concrete (RC) buildings is a critical issue for modern earthquake engineering, because for these structural elements, the current codes provide several geometrical constraints and reinforcement provisions, which may be very complex to implement during the construction phase. To investigate how a construction error might influence the joint behavior, two identical full-scale exterior beam-column joints specimens are built, according to Italian Building Code specifications for the high ductility class, but without the required horizontal ties inside the joint panel. This construction error could be plausible because, according to the design dra…
Stock earnings and bond yields in the US 1871–2017 : The story of a changing relationship
2021
Abstract Using historical data spanning almost 150 years, we examine whether there is a long-run equilibrium relationship between the stock's earnings and bond yields. The novelty of our econometric methodology consists in using a vector error correction model where we allow multiple structural breaks in the equilibrium relationship. The results of our analysis suggest the existence of an equilibrium relationship over 1871–1932 and 1958–2017. On the two historical segments, our analysis finds that the stock's earnings yield followed the bond yield in both the short run and long run, but not the other way around. Perhaps the most important and surprising finding of our empirical study is tha…
- EL EFECTO FISHER Y LA PARIDAD DE INTERÉS REAL. EVIDENCIA PARA LA ECONOMÍA ESPAÑOLA
1999
This paper provides an empirical test of the Fisher effect and of the real interest parity. The objetive is to determinate the behavior of the ex-ante real interest that condicionate the intertemporal savings and investment decisions. The method used is the time series properties of the data, which allows to separate estimation of the long-run equilibrium relationship from the nuisance parameters that characterize the short-run dynamics. The results find support inthe long run for a tax-adjusted Fisher hypothesis but not for the real interest parity. En este trabajo se contrasta empíricamente el cumplimiento de la hipótesis de Fisher y de la paridad de interés real para el caso español. El …
BALANCED VARIABLE ADDITION IN LINEAR MODELS
2018
This paper studies what happens when we move from a short regression to a long regression in a setting where both regressions are subject to misspecification. In this setup, the least-squares estimator in the long regression may have larger inconsistency than the least-squares estimator in the short regression. We provide a simple interpretation for the comparison of the inconsistencies and study under which conditions the additional regressors in the long regression represent a “balanced addition” to the short regression.
Price and volatility dynamics between electricity and fuel costs: Some evidence for Spain
2012
Abstract The purpose of this study is to investigate the causal linkages between the Spanish electricity, Brent crude oil and Zeebrugge (Belgium) natural gas 1-month-ahead forward prices. Following Lutkepohl et al. (2004), we control for the presence of a structural change in the series and then we use the Johansen cointegration test and a vector error correction model (VECM) to embrace the analysis. Additionally, a multivariate generalized autoregressive conditional heteroskedastic (GARCH) model is applied to explore volatility interactions between the three markets involved in the study. Our findings reveal that Brent crude oil and Zeebrugge natural gas forward prices play a prominent rol…
Household optimism and overborrowing
2018
We use Finnish household-level data from 1994 to 2013 to measure how often and what kind of forecast errors households make and how the errors are linked to the households' borrowing behavior and overindebtedness. We find that those households that make the largest optimistic forecast errors have greater debt-to-income ratios. They also are more likely to report that they suffer from excessive debt loads and have problems in coping with their bills. There are no such systematic effects for the households that make pessimistic forecast errors. peerReviewed
The effect of round-off error on long memory processes
2011
We study how the round-off (or discretization) error changes the statistical properties of a Gaussian long memory process. We show that the autocovariance and the spectral density of the discretized process are asymptotically rescaled by a factor smaller than one, and we compute exactly this scaling factor. Consequently, we find that the discretized process is also long memory with the same Hurst exponent as the original process. We consider the properties of two estimators of the Hurst exponent, namely the local Whittle (LW) estimator and the Detrended Fluctuation Analysis (DFA). By using analytical considerations and numerical simulations we show that, in presence of round-off error, both…
Violent Conflict and Online Segregation: An Analysis of Social Network Communication Across Ukraine's Regions
2016
Does the intensity of a social conflict affect political division? Traditionally, social cleavages are seen as the underlying cause of political conflicts. It is clear, however, that a violent conflict itself can shape partisan, social, and national identities. In this paper, we ask whether social conflicts unite or divide the society by studying the effects of Ukraine's military conflict with Russia on online social ties between Ukrainian provinces (oblasts). In order to do that, we collected original data on the cross-regional structure of politically relevant online communication among users of VKontakte social networking site. We analyze the panel of provinces spanning the most active p…