One size does not fit all: Heterogeneous economic impact of integrated pest management practices for mango fruit flies in Kenya—a machine learning approach

Most previous studies evaluating agricultural technology adoption focus on estimating homogeneous average treatment effects across technology adopters. Understanding the heterogeneous effects and drivers of impact heterogeneity should enable interventions to be better targeted to maximise benefits. We apply machine learning using data from a randomised controlled trial to estimate the heterogeneous treatment effect of fruit fly IPM practices (i.e., parasitoids, orchard sanitation, use of food bait, biopesticides, male annihilation technique, and their combinations) in Central Kenya. Results suggest significant heterogeneity in the effect of IPM practices conditioned on household characteristics. The most important covariates explaining differences in treatment effects are wealth, distance to the mango fruit market, age of the household head, labour and experience in mango farming. Results further indicate that those with fewer mango trees benefit more from most IPM practices. Additional analysis across other covariates shows mixed results but generally suggests significant differences between households benefiting the most and those benefiting the least from IPM practices.     

Procedure for the Implementation of the Precautionary Principle in Biosafety Commissions

In order to fulfil their responsibilities under the precautionary principle, biosafety commissions should lay down guidelines concerning the understanding and application of this principle and work towards an operational procedure. With this contribution, we propose a step‐wise procedure that aims to establish the understanding of the precautionary principle within biosafety commissions and to provide a methodological approach for the application of this principle to specific cases in the course of risk assessment. This approach is based on systematically investigating the consensus view within a group of 15 biosafety experts with the help of sets of checklists. For step 1, we propose a checklist of 13 criteria aimed at defining the understanding of the precautionary principle. For step 2, we propose 4 criteria for the decision on whether or not to use the precautionary principle. For step 3, 11 criteria for the use of the precautionary principle are presented. In step 4, additional criteria for specific applications could be included. In step 5, possible recommendations to decision‐making authorities are proposed.     

The quantitative turn in the history of economics: promises,perils and challenges

ABSTRACT

A quantitative turn in history of economic thought is looming. We argue that engineering it consciously is of crucial importance for historians of economics. We also highlight the limitations of quantitative techniques. Yet, the combination of qualitative and quantitative research could substantially enrich our narratives of the development of economics and its practice, of how ideas and tools disseminate and influence other spheres. A failed quantitative turn could lead our field to a house divided and, in the worst case, a civil war.     

Efficiency in wine grape production: comparing long‐established and newly developed regions of South Africa

Efficiency, partly based on technology, is central to international competitiveness. This article applies a stochastic frontier inefficiency model to a panel of 77 wine grape farms in South Africa between 2005 and 2015 and allows the comparison of efficiency levels for the old established wine regions with those of newer entrants. Thus, we investigate whether experience plus first choice of location matters more than the follower's advantage of newer technology. In all regions, a greater share of permanent labor and increased supervision raised efficiency, while more inorganic fertilizer and less irrigation has the opposite effect. Innovations in trellising had insignificant effects (except in the old regions) but not replacing old vines reduced efficiency. However, a higher proportion of red varietals also lowered efficiency in the old regions due to a fall in the price of red wine as these farmers continued to concentrate on quality reds. The new regions compensated for falling prices by increasing crop size with irrigation and fertilizer and extending the area planted, but with less concern for quality. This appears to be more successful in efficiency terms, but as international demand for quality wine increases it may be a poor long‐term strategy.     

Labour Demand in the Post‐apartheid South African Wine Industry

In 2013 the minimum agricultural wage in South Africa was increased by an unprecedented 51%. We use data on 77 Western Cape Province wine grape farms from 2005–2015 to estimate the impacts on employment. Previous post‐apartheid labour market reforms increased minimum wages substantially, but re‐entry to global markets after sanctions were lifted increased demand and this preserved jobs in the wine sector. However, by 2005 this demand growth had largely ceased. The long‐run wage elasticity for permanent employees was found to be ?0.4, but for casual workers the figure was ?4.7, so the 51% wage increase is likely to decimate casual employment in the future. Thus, the poorest and most vulnerable casual workers lose most in terms of jobs, incomes and secure livelihoods, whereas 80% of full‐time staff benefit from the higher minimum wages. Thus, the minimum wage change is likely to increase the gap between privileged permanent staff and casual workers. This result is not surprising in view of the long‐standing interdependence between farmers and their permanent workers in wine grape production.     

District-level total factor productivity in agriculture: Western Cape Province, South Africa, 1952–2002

This article measures total factor productivity (TFP) growth in Western Cape agriculture for 31 magisterial districts from 1952 to 2002 to illustrate the benefits of disaggregation compared with national TFPs. There is negative or low growth in the eastern districts and rapid growth in the western districts. The regions with substantial chicken, pigs, dairy, and, especially, export fruit production grew rapidly, whereas the sheep-dominated Karoo had negative growth. Productivity growth correlates mostly with output mix, which in turn depends on irrigation investment. A similar program will be needed at the national level if prosperity is to be extended to black smallholders who currently lack access to water and other modern infrastructure.     

Multisource Ratings Of Managerial Competencies And Their Predictive Value For Managerial And Organizational Effectiveness

This study examined the predictive value of multisource ratings of managerial competencies for managerial and organizational effectiveness. Data from 155 subordinates, 59 peers, and 28 supervisors were gathered in order to provide insight into their perceptions on managerial competencies for their managers. With regard to the outcome variable (i.e., effectiveness), both individual‐level (subordinates’, peers’, and supervisors’ ratings of managers) and organizational‐level (Balanced Scorecard) measures were used. As expected, subordinates, peers, and supervisors have distinct perspectives on the managerial competencies that are relevant for effectiveness. Moreover, the specific managerial competencies differ in terms of their predictive validity respectively for managerial and organizational effectiveness. The outcomes of our study suggest that a multisource and multimethod approach is valuable in assessing both managerial competencies and managerial and organizational effectiveness. Several implications for human resource management practices are discussed. © 2014 Wiley Periodicals, Inc.     

Strategic Responses: A Survey Experiment on Opposition to Pension Reforms*

The responses given in opinion polls on future policy reforms reflect both subjective expectations and preferences. We disentangle these factors using data from a controlled survey experiment conducted in Germany. At the time of the experiment, an increased retirement age had been proposed as part of a pension reform. Thus, the survey respondents faced an incentive to give biased responses. By understating their expected work ability at the age of retirement, they could make the increase of the retirement age a less attractive policy option. We find evidence for such strategic response behavior, and this strategic bias appears to be stronger in former communist East Germany.