Endogeneity in Panel Stochastic Frontier Models: An Application to the Japanese Cotton Spinning Industry

We present a panel stochastic frontier model that handles the endogeneity problem. This model can treat the endogeneity of both frontier and inefficiency variables. We apply our method to examine the technical efficiency of Japanese cotton spinning industry. Our results indicate that market concentration is endogenous, and when its endogeneity is properly handled, it has a larger negative impact on the technical efficiency of cotton spinning plants. We find that the exogenous model substantially overestimates efficiency in concentrated markets

School district consolidation policies: endogenous cost inefficiency and saving reversals

Some education policy studies suggest that consolidation of public school districts saves resources. However, endogeneity in cost models would result in incorrect estimates of the effects of consolidation. We use a new stochastic frontier methodology to examine district expenditures while handling endogeneity. Using the data from California, we find that the effects of student achievement and education market concentration on expenditure per pupil are substantially larger when endogeneity is handled. Our findings are robust to concerns such as instrumental variable adequacy and spatial interactions. Our consolidation simulations indicate that failure to address endogeneity can result in unrealistic expectations of savings

The Effects of Multi-Dimensional Competition on Education Market Outcomes

In this dissertation, I analyze the effects of competition in education markets. In my first essay, I analyze the effects of different concentration measures on school personnel salaries. I find evidence that principals have more bargaining power over their salaries than teachers in Washington that through rent-sharing, principals start getting positive returns from increasing concentration at lower levels of concentration than that of teachers. Moreover, I present that the pattern of teacher salaries versus concentration in Washington is similar to that in Texas, but the inflection point in Washington is at substantially lower levels of concentration-a finding which can be attributed to Washington's being a union state versus Texas's being a right-to-work-state. In my second essay, I examine the effects of various measures of competition on school district cost inefficiency in a stochastic frontier framework. My results show that cost frontier is U-shaped in Texas with large positive returns to the scale over a relatively big range and mild diseconomies of scale over an extended range. In addition, I find that school district cost inefficiency increases significantly when market concentration increases. Furthermore, I present the competitive effect/scale effect trade-off through a couple of simulation exercises. The findings from both of my studies show that the effects of competition are barely sensitive to measuring the competition with different sets of relevant competitors. On the other hand, sensitivity of the effects of competition to using different definitions of the education markets is significant. Yet, the range of these estimated effects is relatively small, and the sign and the significance of the effect of competition generally do not change when a meaningful definition of education markets is employed to measure concentration. Furthermore, I present that the concentration measures employed in my essays are endogenous. I control for the endogeneity with several instrumental variables including degrees of lagged educational outputs in the neighboring schools, lagged education market characteristics, and counts of streams. My results imply that the hypothesized effects of competition may be underestimated due to the endogeneity. While the plausibility of competitive effect's being underestimated bolsters the importance of the competitive effects I find, it also strengthens my criticism of using uni-dimensional concentration indices as indicators of competition in the education markets

A Dynamic Stochastic Frontier Model with Threshold Effects: U.S. Bank Size and Efficiency

Common/Single frontier methodologies that are used to analyze bank efficiency and performance can be misleading because of the homogeneous technology assumption. Using the U.S. banking data over 1984-2010, our dynamic methodology identifies a few data-driven thresholds and distinct size groups. Under common frontier assumption, the largest banks appear to be 22% less efficient on average than how they are in our model. Also, in the common frontier model, smaller banks seem to be relatively more efficient compared to their larger counterparts. Hence, common policies or regulations may not be well-balanced about controlling the banks of different sizes on the spectrum

The effects of aid on foreign direct investment : the roles of governance and financial market development

Ankara : The Department of Economics, The Institute of Economics and Social Sciences of Bilkent University, 2005.Thesis (Master's) -- Bilkent University, 2005.Includes bibliographical references leaves 70-79.This thesis investigates the effects of aid on foreign direct investment. The study takes into account the conditions such as sound governance within countries or well-developed financial markets, which are expected to effect this relationship. The hypothesis is that aid encourages foreign direct investment only where governance is of quality or financial markets are developed or both. The dynamic relationship is examined using an unbalanced panel data set, including 97 countries over the period of 1960-2004, where available. The results of the empirical analysis confirm the hypothesis with strong evidence.Karakaplan, Mustafa UğurM.S

Case Report Adventitious Bursitis Overlying an Osteochondroma of the Humerus Facing the Thoracic Wall

One of the complications of osteochondromas is the development of a bursa over the cartilaginous cap. We report a 15-year-old boy with a rapidly expanded adventitious bursitis overlying an osteochondroma of the humerus facing the thoracic wall, a location not previously reported for such bursa formation. Magnetic resonance imaging readily showed adventitious bursitis overlying the osteochondroma, thereby dispelling concerns for malignant transformation

Fitting endogenous stochastic frontier models in Stata

In this article, I introduce sfkk, a new command for fitting endogenous stochastic frontier models. sfkk provides estimators for the parameters of a linear model with a disturbance assumed to be a mixture of two components: a measure of inefficiency that is strictly nonnegative and a two-sided error term from a symmetric distribution. sfkk can handle endogenous variables in the frontier or the inefficiency, and the sfkk estimates outperform the standard frontier estimates that ignore endogeneity

Panel stochastic frontier models with endogeneity

In this article, I introduce xtsfkk as a new command for fitting panel stochastic frontier models with endogeneity. The advantage of xtsfkk is that it can control for the endogenous variables in the frontier and the inefficiency term in a longitudinal setting. Hence, xtsfkk performs better than standard panel frontier estimators such as xtfrontier that overlook endogeneity by design. Moreover, xtsfkk uses Mata’s moptimize() functions for substantially faster execution and completion speeds. I also present a set of Monte Carlo simulations and examples demonstrating the performance and usage of xtsfkk

Pseudoaneurysm discovered during reverse radial forearm flap after a gunshot injury: a case report

Gunshots cause injury on the vascular wall by phsical forces and thermal effect. These injuries are minor intimal damage, complete or partial transaction of the vessel, arteriovenoous fistula and pseudoaneurysm. In this article we report a pseudoaneursym case, at a gunshot wound on right hand planned to repair by reverse radial forearm flap for to cover the defect occured at the ipsilateral dorsum of the right hand, which was suspected on CT angiography but missed out preoperatively and seen in surgery during exploration and reparied. [Med-Science 2013; 2(1.000): 414-22