Gradient-based habitat affinities predict species vulnerability to drought.

Ecological fingerprints of climate change are becoming increasingly evident at broad geographical scales as measured by species range shifts and changes in phenology. However, finer-scale species-level responses to environmental fluctuations may also provide an important bellwether of impending future community responses. Here we examined changes in abundance of butterfly species along a hydrological gradient of six montane meadow habitat types in response to drought. Our data collection began prior to the drought, and we were able to track changes for 11 years, of which eight were considered mild to extreme drought conditions. We separated the species into those that had an affinity for hydric vs. xeric habitats. We suspected that drought would favor species with xeric habitat affinities, but that there could be variations in species-level responses along the hydrological gradient. We also suspected that mesic meadows would be most sensitive to drought conditions. Temporal trajectories were modeled for both species groups (hydric vs. xeric affinity) and individual species. Abundances of species with affinity for xeric habitats increased in virtually all meadow types. Conversely, abundances of species with affinity for hydric habitats decreased, particularly in mesic and xeric meadows. Mesic meadows showed the most striking temporal abundance trajectory: Increasing abundances of species with xeric habitat affinity were offset by decreasing or stable abundances of species with hydric habitat affinity. The one counterintuitive finding was that, in some hydric meadows, species with affinity for hydric habitats increased. In these cases, we suspect that decreasing moisture conditions in hydric meadows actually increased habitat suitability because sites near the limit of moisture extremes for some species became more acceptable. Thus, species responses were relatively predictable based upon habitat affinity and habitat location along the hydrological gradient, and mesic meadows showed the highest potential for changes in community composition. The implications of these results are that longer-term changes due to drought could simplify community composition, resulting in prevalence of species tolerant to drying conditions and a loss of species associated with wetter conditions. We contend that this application of gradient analysis could be valuable in assessing species vulnerability of other taxa and ecosystems.

Design, evaluation, and dissemination of a plastic syringe clip to improve dosing accuracy of liquid medications.

Pediatricians in Africa requested a tool to improve caregiver dosing of liquid antiretroviral medication. We developed, evaluated and disseminated a clip to control the amount of medication drawn into an oral syringe. In a laboratory, a user tested clips of different lengths, corresponding to different volumes, by drawing water into a syringe with a clip. In Texas and Malawi, 149 adults attempted to measure Pepto-Bismol™ using a syringe with a clip, a syringe without a clip, and a dosing cup, in a randomly assigned order. In the laboratory, the volume of liquid, ranging from 1 to 4.5 mL, drawn into the syringe was always within at least 5 µL of the intended dose. In Texas, 84% of doses were accurate within ±10%, vs. 63% using the syringe alone, and 21% with the dosing cup. In Malawi, 98% of doses were accurate to within ±10%, vs. 90% using the syringe alone, and 27% with the dosing cup. For target accuracy values within ±45% (±21%), a significantly higher fraction of Houston (Kamangira) participants delivered an accurate dose using the syringe with the clip than with the syringe alone (p < 0.05). The clip enables a greater proportion of users to accurately measure liquid medication.

Product plots.

We propose a new framework for visualising tables of counts, proportions and probabilities. We call our framework product plots, alluding to the computation of area as a product of height and width, and the statistical concept of generating a joint distribution from the product of conditional and marginal distributions. The framework, with extensions, is sufficient to encompass over 20 visualisations previously described in fields of statistical graphics and infovis, including bar charts, mosaic plots, treemaps, equal area plots and fluctuation diagrams.

Graphical inference for Infovis.

How do we know if what we see is really there? When visualizing data, how do we avoid falling into the trap of apophenia where we see patterns in random noise? Traditionally, infovis has been concerned with discovering new relationships, and statistics with preventing spurious relationships from being reported. We pull these opposing poles closer with two new techniques for rigorous statistical inference of visual discoveries. The "Rorschach" helps the analyst calibrate their understanding of uncertainty and "line-up" provides a protocol for assessing the significance of visual discoveries, protecting against the discovery of spurious structure.

Montane meadow change during drought varies with background hydrologic regime and plant functional group.

Climate change models for many ecosystems predict more extreme climatic events in the future, including exacerbated drought conditions. Here we assess the effects of drought by quantifying temporal variation in community composition of a complex montane meadow landscape characterized by a hydrological gradient. The meadows occur in two regions of the Greater Yellowstone Ecosystem (Gallatin and Teton) and were classified into six categories (M1-M6, designating hydric to xeric) based upon Satellite pour l'Observation de la Terre (SPOT) satellite imagery. Both regions have similar plant communities, but patch sizes of meadows are much smaller in the Gallatin region. We measured changes in the percent cover of bare ground and plants by species and functional groups during five years between 1997 and 2007. We hypothesized that drought effects would not be manifested evenly across the hydrological gradient, but rather would be observed as hotspots of change in some areas and minimally evident in others. We also expected varying responses by plant functional groups (forbs vs. woody plants). Forbs, which typically use water from relatively shallow s,oils compared to woody plants, were expected to decrease in cover in mesic meadows, but increase in hydric meadows. Woody plants, such as Artemisia, were expected to increase, especially in mesic meadows. We identified several important trends in our meadow plant communities during this period of drought: (1) bare ground increased significantly in xeric meadows of both regions (Gallatin M6 and Teton M5) and in mesic (M3) meadows of the Teton, (2) forbs decreased significantly in the mesic and xeric meadows in both regions, (3) forbs increased in hydric (M1) meadows of the Gallatin region, and (4) woody species showed increases in M2 and M5 meadows of the Teton region and in M3 meadows of the Gallatin region. The woody response was dominated by changes in Artemisia spp. and Chrysothamnus viscidiflorus. Thus, our results supported our expectations that community change was not uniform across the landscape, but instead could be predicted based upon functional group responses to the spatial and temporal patterns of water availability, which are largely a function of plant water use and the hydrological gradient.

Statistical inference for exploratory data analysis and model diagnostics.

We propose to furnish visual statistical methods with an inferential framework and protocol, modelled on confirmatory statistical testing. In this framework, plots take on the role of test statistics, and human cognition the role of statistical tests. Statistical significance of 'discoveries' is measured by having the human viewer compare the plot of the real dataset with collections of plots of simulated datasets. A simple but rigorous protocol that provides inferential validity is modelled after the 'lineup' popular from criminal legal procedures. Another protocol modelled after the 'Rorschach' inkblot test, well known from (pop-)psychology, will help analysts acclimatize to random variability before being exposed to the plot of the real data. The proposed protocols will be useful for exploratory data analysis, with reference datasets simulated by using a null assumption that structure is absent. The framework is also useful for model diagnostics in which case reference datasets are simulated from the model in question. This latter point follows up on previous proposals. Adopting the protocols will mean an adjustment in working procedures for data analysts, adding more rigour, and teachers might find that incorporating these protocols into the curriculum improves their students' statistical thinking.

Diagnostic value of written referral and/or images for skin lesions.

We examined whether it is possible for a dermatologist to diagnose benign and malignant skin lesions by telemedicine, given a comprehensive history and/or clinical images. A medical student recorded a standardized history and description of 109 skin lesions and took digital photographs of the presenting lesion(s) immediately prior to a normal outpatient dermatology consultation. About 52 dermatologists were invited to participate in online diagnosis. In all, 38 took part and they were provided with the text and/or the image(s) online on a secure Website. When the images and text were provided, 53% of teledermatology diagnoses were the same as the face-to-face diagnosis. When images alone were provided, 57% of diagnoses were the same. When text alone was provided, 41% of diagnoses were the same. The relatively low diagnostic concordance may have been due to the inexperience of many teledermatologists and poor quality image display systems. The teledermatologists were less confident in their diagnoses than face-to-face specialists, especially in the absence of images. The teledermatology management plan was more likely to include biopsy, excision or review than was the case at the face-to-face consultation. Teledermatology may result in an increase in follow-up appointments and surgical procedures.