Effects of Influential Points and Sample Size on the Selection and Replicability of Multivariable Fractional Polynomial Models

The multivariable fractional polynomial (MFP) procedure combines variable selection with a function selection procedure (FSP). For continuous variables, a closed test procedure is used to decide between no effect, linear, FP1 or FP2 functions. Influential observations (IPs) and small sample size can both have an impact on a selected fractional polynomial model. In this paper, we used simulated data with six continuous and four categorical predictors to illustrate approaches which can help to identify IPs with an influence on function selection and the MFP model. Approaches use leave-one or two-out and two related techniques for a multivariable assessment. In seven subsamples we also investigated the effects of sample size and model replicability. For better illustration, a structured profile was used to provide an overview of all analyses conducted. The results showed that one or more IPs can drive the functions and models selected. In addition, with a small sample size, MFP might not be able to detect non-linear functions and the selected model might differ substantially from the true underlying model. However, if the sample size is sufficient and regression diagnostics are carefully conducted, MFP can be a suitable approach to select variables and functional forms for continuous variables.Comment: Main paper and a supplementary combine

Walk on the Wild Side: Estimating the Global Magnitude of Visits to Protected Areas

How often do people visit the world’s protected areas (PAs)? Despite PAs covering one-eighth of the land and being a major focus of nature-based recreation and tourism, we don’t know. To address this, we compiled a globally-representative database of visits to PAs and built region-specific models predicting visit rates from PA size, local population size, remoteness, natural attractiveness, and national income. Applying these models to all but the very smallest of the world’s terrestrial PAs suggests that together they receive roughly 8 billion (8 x 109) visits/y—of which more than 80% are in Europe and North America. Linking our region-specific visit estimates to valuation studies indicates that these visits generate approximately US $600 billion/y in direct in-country expenditure and US$250 billion/y in consumer surplus. These figures dwarf current, typically inadequate spending on conserving PAs. Thus, even without considering the many other ecosystem services that PAs provide to people, our findings underscore calls for greatly increased investment in their conservation.This study was supported by The Natural Capital Project (http://www.naturalcapitalproject.org/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.This is the final published version. It first appeared at http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002074

Walk on the wild side: estimating the global magnitude of visits to protected areas.

How often do people visit the world's protected areas (PAs)? Despite PAs covering one-eighth of the land and being a major focus of nature-based recreation and tourism, we don't know. To address this, we compiled a globally-representative database of visits to PAs and built region-specific models predicting visit rates from PA size, local population size, remoteness, natural attractiveness, and national income. Applying these models to all but the very smallest of the world's terrestrial PAs suggests that together they receive roughly 8 billion (8 x 109) visits/y-of which more than 80% are in Europe and North America. Linking our region-specific visit estimates to valuation studies indicates that these visits generate approximately US $600 billion/y in direct in-country expenditure and US$250 billion/y in consumer surplus. These figures dwarf current, typically inadequate spending on conserving PAs. Thus, even without considering the many other ecosystem services that PAs provide to people, our findings underscore calls for greatly increased investment in their conservation.This study was supported by The Natural Capital Project (http://www.naturalcapitalproject.org/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.This is the final published version. It first appeared at http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002074

Parks and Tourism

To protect biodiversity, parks agencies need political and financial support. Recreational visitors can bring both, but commercial tourism carries risks

Tradeoffs in the externalities of pig production are not inevitable

Farming externalities are believed to co-vary negatively, yet trade-offs have rarely been quantified systematically. Here we present data from UK and Brazilian pig production systems representative of most commercial systems across the world ranging from ‘intensive’ indoor systems through to extensive free range, Organic and woodland systems to explore co-variation among four major externality costs. We found that no specific farming type was consistently associated with good performance across all domains. Generally, systems with low land use have low greenhouse gas emissions but high antimicrobial use and poor animal welfare, and vice versa. Some individual systems performed well in all domains but were not exclusive to any particular type of farming system. Our findings suggest that trade-offs may be avoidable if mitigation focuses on lowering impacts within system types rather than simply changing types of farming

European adult smokers' perceptions of the harmfulness of e-cigarettes relative to combustible cigarettes: cohort findings from the 2016 and 2018 EUREST-PLUS ITC Europe Surveys

Background: This study presents perceptions of the harmfulness of electronic cigarettes (e-cigarettes) relative to combustible cigarettes among smokers from six European Union (EU) countries, prior to the implementation of the EU Tobacco Products Directive (TPD), and 2 years post-TPD. Methods: Data were drawn from the EUREST-PLUS ITC Europe Surveys, a cohort study of adult smokers (>= 18 years) from Germany, Greece, Hungary, Poland, Romania and Spain. Data were collected in 2016 (pre-TPD: N = 6011) and 2018 (post-TPD: N = 6027). Weighted generalized estimating equations were used to estimate perceptions of the harmfulness of e-cigarettes compared to combustible cigarettes (less harmful, equally harmful, more harmful or 'don't know'). Results: In 2016, among respondents who were aware of e-cigarettes (72.2%), 28.6% reported that they perceived e-cigarettes to be less harmful than cigarettes (range 22.0% in Spain to 34.1% in Hungary). In 2018, 72.2% of respondents were aware of e-cigarettes, of whom 28.4% reported perceiving that e-cigarettes are less harmful. The majority of respondents perceived e-cigarettes to be equally or more harmful than cigarettes in both 2016 (58.5%) and 2018 (61.8%, P>0.05). Overall, there were no significant changes in the perceptions that e-cigarettes are less, equally or more harmful than cigarettes, but 'don't know' responses significantly decreased from 12.9% to 9.8% (P = 0.036). The only significant change within countries was a decrease in 'don't know' responses in Spain (19.3-9.4%, P = .001). Conclusions: The majority of respondents in these six EU countries perceived e-cigarettes to be equally or more harmful than combustible cigarettes

A Global Perspective on Trends in Nature-Based Tourism

Falling attendance at United States and Japanese national parks has led to claims of a pervasive shift away from nature-based recreation. A global analysis, however, now suggests that while visit rates are declining slightly in some richer countries, elsewhere nature tourism is booming

Investing in Threatened Species Conservation: Does Corruption Outweigh Purchasing Power?

In many sectors, freedom in capital flow has allowed optimization of investment returns through choosing sites that provide the best value for money. These returns, however, can be compromised in countries where corruption is prevalent. We assessed where the best value for money might be obtained for investment in threatened species that occur at a single site, when taking into account corruption. We found that the influence of corruption on potential investment decisions was outweighed by the likely value for money in terms of pricing parity. Nevertheless global conservation is likely to get best returns in terms of threatened species security by investing in “honest” countries than in corrupt ones, particularly those with a high cost of living

Potential impact of invasive alien species on ecosystem services provided by a tropical forested ecosystem: a case study from Montserrat

Local stakeholders at the important but vulnerable Centre Hills on Montserrat consider that the continued presence of feral livestock (particularly goats and pigs) may lead to widespread replacement of the reserve’s native vegetation by invasive alien trees (Java plum and guava), and consequent negative impacts on native animal species. Since 2009, a hunting programme to control the feral livestock has been in operation. However long-term funding is not assured. Here, we estimate the effect of feral livestock control on ecosystem services provided by the forest to evaluate whether the biodiversity conservation rationale for continuation of the control programme is supported by an economic case. A new practical tool (Toolkit for Ecosystem Service Site-based Assessment) was employed to measure and compare ecosystem service provision between two states of the reserve (i.e. presence and absence of feral livestock control) to estimate the net consequences of the hunting programme on ecosystem services provided by the forest. Based on this we estimate that cessation of feral livestock management would substantially reduce the net benefits provided by the site, including a 46 % reduction in nature-based tourism (from $419,000 to$228,000) and 36 % reduction in harvested wild meat (from $205,000 to$132,000). The overall net benefit generated from annual ecosystem service flows associated with livestock control in thereserve, minus the management cost, was $214,000 per year. We conclude that continued feral livestock control is important for maintaining the current level of ecosystem services provided by the reserve