NEURAL NETWORK AND SEGMENTED LABOUR MARKET

In France, for administrative reasons, unemployed workers may actually be involved in occasional work while remaining identified as unemployed (and receiving the corresponding benefit). This is due to the fact that the unemployed are deemed to be seeking full-time jobs and non-fixed term contracts of employment. This situation may be analysed as evidence of a special type of secondary segment of the labour market in a context of massive unemployment. The authors consider the effects of this situation both on the duration of unemployment and its recurrence may be usefully investigated.

Efficient estimators : the use of neural networks to construct pseudo panels

Pseudo panels constituted with repeated cross-sections are good substitutes to true panel data. But individuals grouped in a cohort are not the same for successive periods, and it results in a measurement error and inconsistent estimators. The solution is to constitute cohorts of large numbers of individuals but as homogeneous as possible. This paper explains a new way to do this: by using a self-organizing map, whose properties are well suited to achieve these objectives. It is applied to a set of Canadian surveys, in order to estimate income elasticities for 18 consumption functions..Pseudo panels ; self-organizing maps;

CLASSIFICATION OF RECURRING UNEMPLOYED WORKERS AND UNEMPLOYMENT EXITS

This study focuses on recurring unemployment, that is people with two or more spells of unemployment during the period of observation (July 1993 – August 1996). First, a classification is obtained which is then used to examine the specific role of occasional jobs during a spell of unemployment and, in this context, the influence of the received unemployment benefits on the duration of this spell. This paper is a continuation of previous analyses of unemployment in France, based on long-term data from the unemployed register held by ANPE (National Employment Bureau). The present analysis conducted using additional information about unemployment benefits received by the unemployed from UNEDIC (Unemployment Benefits Office).Unemployment, Labor Market, Kohonen Maps

A DYNAMIC ANALYSIS OF SEGMENTED LABOR MARKET

Using the Panel Study of Income Dynamics data on the period 1982-1992, this paper investigates some mechanisms of the labor market in the United States. This market is analyzed as a stable structure constituted of segments which present contrasted characteristics under the usual distinction between primary and secondary sectors. Using a neural network algorithm applied on quantitative variables measured at the level of heads of household, a broad classification in four classes of situations is constructed. It shows a clear hierarchy going from situations of very precarious work or no work at all, to situations of stable jobs with higher wages than the average. A Markov chain, constructed with the trajectories between the different situations of these workers, shows a very stable structure of this segmented labor market. Keywords: segmented labor market, unemployment, trajectories, Kohonen algorithm, Markov chain.Keywords: segmented labor market, unemployment, trajectories, Kohonen algorithm, Markov chain.

Analysis of Professional Trajectories using Disconnected Self-Organizing Maps

In this paper we address an important economic question. Is there, as mainstream economic theory asserts it, an homogeneous labor market with mechanisms which govern supply and demand for work, producing an equilibrium with its remarkable properties? Using the Panel Study of Income Dynamics (PSID) collected on the period 1984-2003, we study the situations of American workers with respect to employment. The data include all heads of household (men or women) as well as the partners who are on the labor market, working or not. They are extracted from the complete survey and we compute a few relevant features which characterize the worker's situations. To perform this analysis, we suggest using a Self-Organizing Map (SOM, Kohonen algorithm) with specific structure based on planar graphs, with disconnected components (called D-SOM), especially interesting for clustering. We compare the results to those obtained with a classical SOM grid and a star-shaped map (called SOS). Each component of D-SOM takes the form of a string and corresponds to an organized cluster. From this clustering, we study the trajectories of the individuals among the classes by using the transition probability matrices for each period and the corresponding stationary distributions. As a matter of fact, we find clear evidence of heterogeneous parts, each one with high homo-geneity, representing situations well identified in terms of activity and wage levels and in degree of stability in the workplace. These results and their interpretation in economic terms contribute to the debate about flexibility which is commonly seen as a way to obtain a better level of equilibrium on the labor market

Expression of IRBIT Along the Rat Gastrointestinal Tract

IRBIT (inositol-1,4,5-trisphosphate (IP3) receptors binding protein released with IP3) regulates fluid transport in the pancreatic duct and other epithelial cells. Most of the research done on IRBIT focuses on what transporters and channels IRBIT regulates. Much less is known about what regulates IRBIT and its distribution along the gastrointestinal tract. In the present study, we aim to determine the expression of IRBIT in the gastrointestinal (GI) tract and accessory glands such as the liver and pancreas. IRBIT has two isoforms- a short and a long. To date, antibodies are unable to differentiate between the two, so a different approach is required. PCR (polymerase chain reaction) with specific primers for each isoform will be used. We have harvested stomach, duodenum, jejunum, ileum, proximal and distal colon from male rats. Using a phosphate buffered saline solution containing zero calcium, we have selectively isolated the epithelial cells from each of the aforementioned segments of the GI tract. Using western blot, we found that IRBIT is expressed in duodenum, jejunum, ileum, proximal and distal colon. To test the expression of the short and long IRBIT, using a similar technique we have isolated epithelial cells from stomach, duodenum, jejunum, ileum, proximal and distal colon. Using Trizol-chloroform we have selectively isolated the total mRNA from each tissue. In future experiments, we will make a cDNA library from each tissue to perform PCR and determine the expression of short and long IRBIT

Dynamical Equilibrium, trajectories study in an economical system. The case of the labor market

The paper deals with the study of labor market dynamics, and aims to characterize its equilibriums and possible trajectories. The theoretical background is the theory of the segmented labor market. The main idea is that this theory is well adapted to interpret the observed trajectories, due to the heterogeneity of the work situations.Comment: accepted to the WSOM 2007 Conference (Bielefield