Social-Family Network and Self-Employment: Evidence from Temporary Rural-Urban Migrants in China

We hypothesize that individuals with a larger social-family network are more likely to choose self-employment. We test this hypothesis using data on temporary rural-urban migrants in China. The size of a migrant’s social-family network is measured by the number of relatives and friends this migrant greeted during the past Spring Festival. Our empirical analysis faces two challenges. First, there is an endogeneity problem in that a migrant may want to develop and maintain a large social-family network exactly because he is self-employed. For this reason, a simple correlation between the probability of being self-employed and the size of the migrant’s social-family network cannot be interpreted as causal. Second, the size of the social-family network is measured using survey data, which is subject to measurement error. To overcome these problems, we take an instrumental variable (IV) approach. More specifically, we examine the distance an individual migrated when he first moved to a city and use this variable to instrument for the current size of the social-family network. We establish the credibility of the IV by emphasizing the unique institutional context of rural-urban migration in China and focusing on the sample of migrants who originally started as wage workers in urban areas and currently are not in their first jobs. Our IV results indeed show that a rural-urban migrant with a larger social-family network is more likely to be self-employed in the city. This finding is robust to alternative model specifications and various restrictions on the sample used in estimation.social-family network, self-employment, rural-urban migrants

Do Small Businesses Create More Jobs? New Evidence for the United States from the National Establishment Time Series

We use a new database, the National Establishment Time Series (NETS), to revisit the debate about the role of small businesses in job creation. Birch (e.g., 1987) argued that small firms are the most important source of job creation in the U.S. economy. But Davis et al. (1996a) argued that this conclusion was flawed, and based on improved methods and using data for the manufacturing sector, they concluded that there was no relationship between establishment size and net job creation. Using the NETS data, we examine evidence for the overall economy, as well as for different sectors. The results indicate that small firms and small establishments create more jobs, on net, although the difference is much smaller than what is suggested by Birch's methods. Moreover, in the recent period we study, a negative relationship between establishment size and job creation holds for both the manufacturing and services sectors.job creation, job destruction, small businesses

The Effects of Wal-Mart on Local Labor Markets

We estimate the effects of Wal-Mart stores on county-level retail employment and earnings, accounting for endogeneity of the location and timing of Wal-Mart openings that most likely biases the evidence against finding adverse effects of Wal-Mart stores. We address the endogeneity problem using a natural instrumental variables approach that arises from the geographic and time pattern of the opening of Wal-Mart stores, which slowly spread out from the first stores in Arkansas. The employment results indicate that a Wal-Mart store opening reduces county-level retail employment by about 150 workers, implying that each Wal-Mart worker replaces approximately 1.4 retail workers. This represents a 2.7 percent reduction in average retail employment. The payroll results indicate that Wal-Mart store openings lead to declines in county-level retail earnings of about $1.2 million, or 1.3 percent. Of course, these effects occurred against a backdrop of rising retail employment, and only imply lower retail employment growth than would have occurred absent the effects of Wal-Mart.Wal-Mart; Employment

The Effects of Wal-Mart on Local Labor Markets

We estimate the effects of Wal-Mart stores on county-level retail employment and earnings, accounting for endogeneity of the location and timing of Wal-Mart openings that most likely biases the evidence against finding adverse effects of Wal-Mart stores. We address the endogeneity problem using a natural instrumental variables approach that arises from the geographic and time pattern of the opening of Wal-Mart stores, which slowly spread out from the first stores in Arkansas. The employment results indicate that a Wal-Mart store opening reduces county-level retail employment by about 150 workers, implying that each Wal-Mart worker replaces approximately 1.4 retail workers. This represents a 2.7 percent reduction in average retail employment. The payroll results indicate that Wal-Mart store openings lead to declines in county-level retail earnings of about $1.4 million, or 1.5 percent. Of course, these effects occurred against a backdrop of rising retail employment, and only imply lower retail employment growth than would have occurred absent the effects of Wal-Mart.

Tipping and Residential Segregation: A Unified Schelling Model

This paper presents a Schelling-type checkerboard model of residential segregation formulated as a spatial game. It shows that although every agent prefers to live in a mixed-race neighborhood, complete segregation is observed almost all of the time. A concept of tipping is rigorously defined, which is crucial for understanding the dynamics of segregation. Complete segregation emerges and persists in the checkerboard model precisely because tipping is less likely to occur to such residential patterns. Agent-based simulations are used to illustrate how an integrated residential area is tipped into complete segregation and why this process is irreversible. This model incorporates insights from Schelling's two classical models of segregation (the checkerboard model and the neighborhood tipping model) and puts them on a rigorous footing. It helps us better understand the persistence of residential segregation in urban America.residential segregation, tipping, checkerboard model

Do Small Businesses Create More Jobs? New Evidence from the National Establishment Time Series

We use a new database, the National Establishment Time Series (NETS), to revisit the debate about the role of small businesses in job creation. Birch (e.g., 1987) argued that small firms are the most important source of job creation in the U.S. economy, but Davis et al. (1996a) argued that this conclusion was flawed, and based on improved methods and using data for the manufacturing sector they concluded that there was no relationship between establishment size and net job creation. Using the NETS data, we examine evidence for the overall economy, as well as for different sectors. The results indicate that small establishments and small firms create more jobs, on net, although the difference is much smaller than what is suggested by Birch's methods. However, the negative relationship between establishment size and job creation is much less clear for the manufacturing sector, which may explain some of the earlier findings contradicting Birch's conclusions.

Research on Heat Transfer Inside the Furnace of Large Scale CFB Boilers

Field tests in one unit of 135MWe and two units of 300MWe commercial Circulating Fluidized bed (CFB) boilers (A&B) with different structures were carried out. The influence of operating conditions on the thermal boundary layer, local heat transfer coefficient and peripheral distribution of heat transfer coefficient were studied. It was found that, in the 135MWe and 300MWe-A CFB furnace, the thickness of the thermal boundary layer was almost constant, about 100mm, and independent of the height above the distributor and the boiler load. The local heat transfer coefficient increased with increasing load as well as the coal feeding rate and air volume in both the 135MWe and 300MWe-A CFB boilers. The boiler structure and heating surface layout had a great influence on the distribution of the heat transfer coefficient in the large-scale CFB boilers. In both the 135MWe furnace and the 300MWe-B CFB boilers, the heat transfer coefficient was lower in the center than near the corner due to higher suspension density in the corner. In the 300MWe-B CFB with heating surfaces in the furnace, because of the uneven layout of the heating surface and the mal-distribution of gas-solid flow caused by the asymmetric arrangement of cyclones, heat transfer coefficients tended to be higher in the middle part than at the walls

The effect of housing wealth on labor force participation: evidence from China

This paper uses the 2011 China Household Finance Survey data to estimate the effect of change in housing value on homeowners’ labor force participation. Using the average housing capital gains of other homes in the same community as an instrument for the housing capital gains of a given household, we find that a 100 thousand yuan increase in housing value leads to a 1.37 percentage point decrease in female homeowners’ probability of participating in the labor force and a 1.49 percentage point increase in their probability of becoming housewives. We find little effect on men’s labor force participation

Coal Ignition Temperature in Oxygen-Enriched CFB Boiler

The oxygen-enriched Circulating fluidized bed (CFB) combustion technology is a new method to reduce CO2 emissions. The coal ignition temperature, Ti F, in an oxygen-enriched CFB boiler is an important parameter for designing the startup burner and for choosing the operating strategy during the startup process. The combustion of five types of coal under four different atmospheres (air, O2 27 %, O2 40%, O2 53%, CO2 as balance gas) was measured in a laboratory scale fluidized bed (FB) with an under-bed preheat system. Using thermocouples and a Gas Analyzer, the changes in bed temperature and the concentration of the different components, such as O2, CO2 and CO, in flue gas were directly measured to determine Ti F. It was found that Ti F decreased with increasing O2 concentration. The differences between the ignition temperatures determined in air and with 27 % O2 were not significant. At lower bed temperatures, for two coal types with higher volatiles, a two stage-ignition for volatiles and char was observed under a high O2 concentration. The time delay between the two stages decreased and finally merged into one with increasing bed temperature. Similar results were obtained in air. The coal with the higher volatile content had a lower ignition temperature in an oxygen-enriched CFB. Comparison of the ignition temperatures obtained by different methods and the feed temperatures in industrial CFB boilers showd that the measured result in a fluidized bed can be used as a reference for oxygen-enriched CFB boilers

The effect of housing wealth on labor force participation: evidence from China

This paper uses the 2011 China Household Finance Survey data to estimate the effect of change in housing value on homeowners’ labor force participation. Using the average housing capital gains of other homes in the same community as an instrument for the housing capital gains of a given household, we find that a 100 thousand yuan increase in housing value leads to a 1.37 percentage point decrease in female homeowners’ probability of participating in the labor force and a 1.49 percentage point increase in their probability of becoming housewives. We find little effect on men’s labor force participation