The impact of demographic change on U. S. labor markets

According to the U. S. Census Bureau projections, the United States will face dramatic demographic changes over the next one hundred years. Indeed, the country will be entering largely uncharted territory. In the twenty-first century, the population is expected to grow more slowly than ever before over an extended period. The population will also age rapidly, with the share of the population over 65 climbing to a succession of new record highs. Finally, the United States will once again become a nation of immigrants. Over the past decade, the wave of new immigrants has already neared proportions last seen in the early 1900s at the end of the Great Migrations. And this inflow is projected to persist throughout the coming century, with new immigrants and the children of those immigrants contributing well over half of the increase in the U. S. population. Because the source of this inflow has shifted from Europe to Latin America and Asia, this new wave will change the voice and face of America forever.Demography ; Economic conditions ; Labor market

Seismic shifts: the economic impact of demographic change: an overview

Most economic developments are hard to predict. Considerable uncertainty surrounds forecasts for output growth, inflation, and unemployment a year from now, for instance. But demographic developments are different in this respect. Although demographic surprises abound, the major trends build slowly, and the broad contours of medium-term outcomes become discernible well in advance.Demography ; Economic conditions

A new approach to causality and economic growth.

This paper examines the issue of causality in cross-sectional empirical models of economic growth. Using an approach to determining causal structures based on tests for conditional independence in sets of variables, we uncover alternative causal structures that are consistent with the correlation pattern of the variables in the data. We use these methods to develop alternative causal empirical models of economic growth. One of our consistent findings is that we can rule out the possibility that equipment investment causes growth. Our search procedure leads naturally to a structural model with latent variables which we then estimate. The results of our estimation are broadly consistent with traditional models of economic growth augmented for human capital.Economic development ; Econometric models

Automated Approaches for Program Verification and Repair

Formal methods techniques, such as verification, analysis, and synthesis,allow programmers to prove properties of their programs, or automatically derive programs from specifications. Making such techniques usable requires care: they must provide useful debugging information, be scalable, and enable automation. This dissertation presents automated analysis and synthesis techniques to ease the debugging of modular verification systems and allow easy access to constraint solvers from functional code. Further, it introduces machine learning based techniques to improve the scalability of off-the-shelf syntax-guided synthesis solvers and techniques to reduce the burden of network administrators writing and analyzing firewalls. We describe the design and implementationof a symbolic execution engine, G2, for non-strict functional languages such as Haskell. We extend G2 to both debug and automate the process of modular verification, and give Haskell programmers easy access to constraints solvers via a library named G2Q. Modular verifiers, such as LiquidHaskell, Dafny, and ESC/Java,allow programmers to write and prove specifications of their code. When a modular verifier fails to verify a program, it is not necessarily because of an actual bug in the program. This is because when verifying a function f, modular verifiers consider only the specification of a called function g, not the actual definition of g. Thus, a modular verifier may fail to prove a true specification of f if the specification of g is too weak. We present a technique, counterfactual symbolic execution, to aid in the debugging of modular verification failures. The approach uses symbolic execution to find concrete counterexamples, in the case of an actual inconsistency between a program and a specification; and abstract counterexamples, in the case that a function specification is too weak. Further, a counterexample-guided inductive synthesis (CEGIS) loop based technique is introduced to fully automate the process of modular verification, by using found counterexamples to automatically infer needed function specifications. The counterfactual symbolic execution and automated specification inference techniques are implemented in G2, and evaluated on existing LiquidHaskell errors and programs. We also leveraged G2 to build a library, G2Q, which allows writing constraint solving problemsdirectly as Haskell code. Users of G2Q can embed specially marked Haskell constraints (Boolean expressions) into their normal Haskell code, while marking some of the variables in the constraint as symbolic. Then, at runtime, G2Q automatically derives values for the symbolic variables that satisfy the constraint, and returns those values to the outside code. Unlike other constraint solving solutions, such as directly calling an SMT solver, G2Q uses symbolic execution to unroll recursive function definitions, and guarantees that the use of G2Q constraints will preserve type correctness. We further consider the problem of synthesizing functions viaa class of tools known as syntax-guided synthesis (SyGuS) solvers. We introduce a machine learning based technique to preprocess SyGuS problems, and reduce the space that the solver must search for a solution in. We demonstrate that the technique speeds up an existing SyGuS solver, CVC4, on a set of SyGuS solver benchmarks. Finally, we describe techniques to ease analysis and repair of firewalls.Firewalls are widely deployed to manage network security. However, firewall systems provide only a primitive interface, in which the specification is given as an ordered list of rules. This makes it hard to manually track and maintain the behavior of a firewall. We introduce a formal semantics for iptables firewall rules via a translation to first-order logic with uninterpreted functions and linear integer arithmetic, which allows encoding of firewalls into a decidable logic. We then describe techniques to automate the analysis and repair of firewalls using SMT solvers, based on user provided specifications of the desired behavior. We evaluate this approach with real world case studies collected from StackOverflow users

U. S. labor supply in the twenty-first century

The American labor force will be transformed as the twenty-first century unfolds, a change that will confront policymakers and business firms with new challenges and new opportunities. The impending slowdown of labor force growth that will accompany the retirement of the baby boom generation already is playing a central role in national debates over the future solvency of Social Security and Medicare, as well as U.S. immigration policies. But labor supply changes will be influenced by other dimensions as well. In the coming decades, American workers are likely to be, on average, older and better educated than today’s labor force. The globalization of labor markets is already opening new employment opportunities for some Americans and changing the wage rates paid to others. The production technologies and personnel policies adopted by tomorrow’s firms will undoubtedly reflect the numbers and types of workers available for employment.Labor supply ; Baby boom generation

Product launch performance in hi-tech SMEs: newness to the firm and the role of management controls

We investigate the impact of management control mechanisms on the success of new product launches in high-technology small- and medium-sized enterprises (SMEs). We argue that internal management controls will alleviate problems associated with product newness. Using survey data from 76 SMEs we find newness to the firm to be negatively related to product launch success, while the use of informal and formal controls have positive effects. Furthermore, informal controls within the SME moderate the negative relationship between newness and launch success. The results add to the debate on the impact of control mechanisms on innovative activities in SMEs

Do State Economics or Individual Characteristics Determine Whether Older Men Work?

The difference in labor force participation rates of men aged 55-64 across the United States is astounding. For example, West Virginia has a participation rate below 60 percent, while South Dakota has a participation rate approaching 90 percent (see Figure 1). This fact in itself has significant implications for the pressures that states will face as the baby boom starts to retire in the face of a contracting retirement income system, declining housing prices, and a lackluster stock market. Despite these marked differences, little is known about the reasons for such variations in work patterns. An earlier brief, using the Current Population Survey for the period 1977-2007, demonstrated that the differences in the labor force participation of older men were related to labor market conditions, the nature of employment, and the employee characteristics in each state as well as to a “pseudo replacement rate.” These variables explained more than one-third of the total variation...