Estimates of the return to schooling in Sweden from a large sample of twins

A large sample of twins was used to examine whether conventional estimates of the return to schooling in Sweden are biased because ability is omitted from the earnings–schooling relationship. Ignoring measurement error, the results indicate that omitting ability from the earnings–schooling relationship leads to estimates that are positively biased. However, reasonable estimates of the measurement-error-adjusted returns are both above and below the unadjusted estimates, showing that the results depend crucially on a parameter not known at this time. However, an estimate of the reliability ratio was obtained using two measures on educational attainment. With this estimate of the reliability ratio, the measurement-error-adjusted estimate of the return to schooling in the sample of identical twins indicates that there is at most a slight ability bias in the conventional estimates of the return to schooling. The fundamental assumption of this kind of study is that within-pair differences in educational attainment are randomly determined. This assumption was also tested, but no strong evidence to reject it was found.     

Marginal taxation on labour income in Sweden from 1862 to 2010

This paper presents annual Swedish time series data on the top marginal tax wedge and marginal tax wedges on labour income for a low-, average- and high-income earner for the period 1862–2010. These data are unique in their consistency, thoroughness and timespan covered. We identify four distinct periods separated by major tax reforms. The tax system can be depicted as proportional, with low tax wedges until the Second World War. Next follows a period featuring increasing tax wedges. During the third period, starting with the 1971 tax reform and continuing throughout the 1980s, the efforts to redistribute income culminated and tax wedges peaked. The high-income earner started to pay the top marginal tax wedge which could be as high as almost 90%. The main explanations for this development are temporary crises leading to permanent tax increases, expansion of the public sector, distributional ambitions, increased local taxes, bracket-creep and the introduction of social security contributions paid by employers. The 1990–1991 tax reform represents the beginning of a new and still continuing period with decreasing marginal tax wedges.     

Forecasting levels of log variables in vector autoregressions

Sometimes forecasts of the original variable are of interest, even though a variable appears in logarithms (logs) in a system of time series. In that case, converting the forecast for the log of the variable to a naïve forecast of the original variable by simply applying the exponential transformation is not theoretically optimal. A simple expression for the optimal forecast under normality assumptions is derived. However, despite its theoretical advantages, the optimal forecast is shown to be inferior to the naïve forecast if specification and estimation uncertainty are taken into account. Hence, in practice, using the exponential of the log forecast is preferable to using the optimal forecast.     

Trade protection and balance of payments problems

A model to be used for planning short-term in-patient medical care is presented. The individual clinic is treated as a production unit which produces different kinds of treated wardcases with a given technique of production (given production-cost-structure). It is assumed to maximize the yearly number of treated wardcases under the constraints of (1) The yearly demand for different kinds of treated wardcases, which is assumed to be proportional to the number of citizens within the area which the clinic serves (the clinics population), (2) The yearly budget which is assigned by public authorities and has to cover all costs as the medical care is supplied free of charge, (3) The clinics physical capacity, measured by the number of beds.

The model has been applied to the branch of general medicine using the estimated production-cost-structure at an existing clinic within this branch. The kind of information that one can get is illustrated, for example: Given a clinic with a certain technique of production (production-cost-structure) which optimizes its production in the way that the model assumes, what is the marginal effects of changes in the size of budget, physical capacity or the size of population? In the case of an existing clinic, perhaps it serves too big a population (the marginal effect of reducing this constraint is zero)? or, when establishing a given kind of clinic what is the best combination of population size, size of budget and physical capacity? How much of the demand will be unsatisfied with different combinations, i.e. how large will the queues become?     

WILDLIFE MANAGEMENT IN ZIMBABWE: EVIDENCE FROM A CONTINGENT VALUATION STUDY

If communities living adjacent to the elephant see it as a burden, then they cannot be its stewards. To assess their valuation of it, a contingent valuation method study was conducted for one CAMPFIRE district in Zimbabwe. Respondents were classified according to their preferences over the elephant. The median willingness to pay for the preservation of 200 elephants is ZW$260 (US$4.73) for respondents who considered the elephant a public good and ZW$137 (US$2.49) for those favouring its translocation. The preservation of 200 elephants yields an annual net worth of ZW$10,828 (US$196) to CAMPFIRE households. However, the majority of households (62%) do not support elephant preservation. This is one argument against devolution of elephant conservation. External transfers constitute one way of providing additional economic incentives to local communities.