| 1. |
- Heshmati, Almas, et al.
(författare)
-
A General Model of Technical Change with an Application to the OECD Countries
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the neoclassical production functions model technical change (TC) is assumed to be exogenous and it is specified as a function of time. However, some exogenous external factors other than time can also affect the rate of TC. In this paper we model TC via a combination of time trend (purely non-economic) and other observable exogenous factors, which we call technology shifters (economic factors). We use several composite technology indices based on appropriate combinations of the external economic factors which are indicators of different aspects of technology. These technology indices are embedded into the production function in such a way that they can complement to different inputs. By estimating the generalized production function, we get estimates of TC which is decomposed TC into a pure time component as well as several producer specific external economic factors. Furthermore, the technology shifters allow for non-neutral and biased shifts in TC. We also consider a simple model in which the technology shifters are aggregated into one single index. The empirical model uses panel data on OECD, accession and enhanced engagement countries observed during 1980-2006.
|
|
| 2. |
- Heshmati, Almas, et al.
(författare)
-
Estimation of firm-specific technological bias, technical change and total factor productivity growth : a dual approach
- 2000
-
Ingår i: Econometric reviews. - : Marcel Dekker, Inc. - 1532-4168 .- 0747-4938. ; 19:4, s. 162-173
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with modeling firm-specific technical change (TC), and technological biases (inputs and scale) in estimating total factor productivity (TFP) growth. Several dual parametric econometric models are used for this purpose. We examine robustness of TFP growth and TC among competing models. These models include the traditional time trend (TT) model and the general index (GI) model. The TT and the GI models are generalized to accommodate firm-specific TC and technological bias (in inputs and output). Both nested and non-nested tests are used to select the appropriate models. Firm-level panel data from the Japanese chemical industry during 1968- 1987 is used as an application.
|
|
| 3. |
- Heshmati, Almas, et al.
(författare)
-
Estimation of productivity in Korean electric power plants : A semiparametric smooth coefficient model
- 2014
-
Ingår i: Energy Economics. - : Elsevier BV. - 0140-9883 .- 1873-6181. ; 45, s. 491-500
-
Tidskriftsartikel (refereegranskat)abstract
- This paper analyzes the impact of load factor, facility and generator types on the productivity of Korean electric power plants. In order to capture important differences in the effect of load policy on power output, we use a semiparametric smooth coefficient (SPSC) model that allows us to model heterogeneous performances across power plants and over time by allowing underlying technologies to be heterogeneous. The SPSC model accommodates both continuous and discrete covariates. Various specification tests are conducted to assess the performance of the SPSC model. Using a unique generator level panel dataset spanning the period 1995-2006, we find that the impact of load factor, generator and facility types on power generation varies substantially in terms of magnitude and significance across different plant characteristics. The results have strong implications for generation policy in Korea as outlined in this study. (C) 2014 Elsevier B.V. All rights reserved.
|
|
| 4. |
- Heshmati, Almas, et al.
(författare)
-
Estimation of Productivity in Korean Electric Power Plants: A Semiparametric Smooth Coefficient Model
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper analyzes the impact of load factor, facility and generator types on the productivity of Korean electric power plants. In order to capture important differences in the effect of load policy on power output, we use a semiparametric smooth coefficient (SPSC) model that allows us to model heterogeneous performances across power plants and over time by allowing underlying technologies to be heterogeneous. The SPSC model accommodates both continuous and discrete covariates. Various specification tests are conducted to compare performance of the SPSC model. Using a unique generator level panel dataset spanning the period 1995-2006, we find that the impact of load factor, generator and facility types on power generation varies substantially in terms of magnitude and significance across different plant characteristics. The results have strong implication for generation policy in Korea as outlined in this study.
|
|
| 5. |
|
|
| 6. |
- Heshmati, Almas, et al.
(författare)
-
Persistent and transient efficiency of international airlines
- 2018
-
Ingår i: European Journal of Transport and Infrastructure Research. - : Technische Universiteit Delft. - 1567-7133 .- 1567-7141. ; 18:2, s. 213-238
-
Tidskriftsartikel (refereegranskat)abstract
- This paper examines the efficiency of international airlines for the period 1998-2012 using some competing stochastic frontier (SF) panel data models. It estimates a cost function for multi-output airline services, separating passenger and goods transportation at the national and international levels. Our preferred SF model distinguishes airlines heterogeneity from time-invariant persistent inefficiency, and transient (time-varying) inefficiency from random the noise component. This four component SF model is compared with two other competing SF models in which one of the four components is missing. All the models are estimated using the maximum likelihood method. The models give predicted values of persistent, transient and overall efficiency for each airline and time period. The mean and dispersion of cost efficiency amongst airlines differ by model specifications and according to their geographical area of operations. The performance difference may be a consequence of different market structures and deregulation processes and of specific competitive conditions such as resource availability and strategic alliances with competitors. The results confirm that, in general, none of the airlines is able to achieve full cost efficiency. We find that carriers based in the Asia region are more efficient than those operating in the European and North American regions. The bigger airlines are unable to take full advantage of economies of scale and are not more efficient than their smaller cousins.
|
|
| 7. |
- Heshmati, Almas, et al.
(författare)
-
Technical Change and Total Factor Productivity Growth: The Case of Chinese Provinces
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the literature technical change is mostly assumed to be exogenous and specified as a function of time. However, some exogenous external factors other than time can also affect technical change. In this paper we model technical change via time trend (purely external non-economic) as well as other exogenous (external economic) factors (technology shifters). We define technology index based on the external economic factors which are indicators of ¡®technology¡¯. Thus our definition of production function is amended to accommodate everal technology shifters which are not separable from the traditional inputs. That is, these technology shifters allow for non-neutral shift in the production function. In doing so we are able to decompose technical change (a component of TFP change) into two parts. One part is driven by time (manna from heaven) and the other part is related to producer specific external economic factors. These exogenous technology shifters are aggregated (via hedonic aggregator functions) into several groups (technology indices) for parsimonious parametric specification. The empirical model uses panel data on Chinese provinces. We identify a number of key technology shifters and their effect on technical change and TFP growth of provinces.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
