0000000000476404
AUTHOR
Jarno Vanhatalo
Calibrating Expert Assessments Using Hierarchical Gaussian Process Models
Expert assessments are routinely used to inform management and other decision making. However, often these assessments contain considerable biases and uncertainties for which reason they should be calibrated if possible. Moreover, coherently combining multiple expert assessments into one estimate poses a long-standing problem in statistics since modeling expert knowledge is often difficult. Here, we present a hierarchical Bayesian model for expert calibration in a task of estimating a continuous univariate parameter. The model allows experts' biases to vary as a function of the true value of the parameter and according to the expert's background. We follow the fully Bayesian approach (the s…
Optimal design of observational studies: overview and synthesis
We review typical design problems encountered in the planning of observational studies and propose a unifying framework that allows us to use the same concepts and notation for different problems. In the framework, the design is defined as a probability measure in the space of observational processes that determine whether the value of a variable is observed for a specific unit at the given time. The optimal design is then defined, according to Bayesian decision theory, to be the one that maximizes the expected utility related to the design. We present examples on the use of the framework and discuss methods for deriving optimal or approximately optimal designs.
Climate change reshuffles northern species within their niches
Climate change is a pervasive threat to biodiversity. While range shifts are a known consequence of climate warming contributing to regional community change, less is known about how species' positions shift within their climatic niches. Furthermore, whether the relative importance of different climatic variables prompting such shifts varies with changing climate remains unclear. Here we analysed four decades of data for 1,478 species of birds, mammals, butterflies, moths, plants and phytoplankton along a 1,200 km high latitudinal gradient. The relative importance of climatic drivers varied non-uniformly with progressing climate change. While species turnover among decades was limited, the …
Landscape structure, habitat quality and metapopulation structure as predictors of population size of the Glanville fritillary butterfly
Spatial variation in population size is affected by many factors, which makes it hard to evaluate the appropriateness of empirical models of population sizes or range dynamics. To complicate matters further in dynamic and spatially structured populations, such as metapopulations, spatial interactions via dispersal as well as local extinctions and colonizations confound the effects of environmental factors. Additionally, while a wealth of ”coarse” environmental data are available for most terrestrial ecosystems it is difficult to know how adequate such data are for explaining abundance compared to situations where more detailed habitat and demographic data are also available. The acquisition…