Exploring spatial variation and spatial relationships in a freshwater acidification critical load data set for Great Britain using geographically weighted summary statistics

2010 ◽  
Vol 36 (1) ◽  
pp. 54-70 ◽  
Author(s):  
Paul Harris ◽  
Chris Brunsdon
Keyword(s):  
Great Britain ◽  
Spatial Variation ◽  
Critical Load ◽  
Spatial Relationships ◽  
Summary Statistics ◽  
Data Set ◽  
Freshwater Acidification

Determinants of spatial variation in fire return period in a semiarid African savanna

2011 ◽  
Vol 20 (4) ◽  
pp. 540 ◽  
Author(s):  
T. G. O'Connor ◽  
C. M. Mulqueeny ◽  
P. S. Goodman
Keyword(s):  
Spatial Variation ◽  
Return Period ◽  
Vegetation Type ◽  
Fire Frequency ◽  
Fuel Load ◽  
Annual Rainfall ◽  
Vegetation Types ◽  
Terrestrial Vegetation ◽  
African Savanna ◽  
Data Set

Fire pattern is predicted to vary across an African savanna in accordance with spatial variation in rainfall through its effects on fuel production, vegetation type (on account of differences in fuel load and in flammability), and distribution of herbivores (because of their effects on fuel load). These predictions were examined for the 23 651-ha Mkuzi Game Reserve, KwaZulu-Natal, based on a 37-year data set. Fire return period varied from no occurrence to a fire every 1.76 years. Approximately 75% of the reserve experienced a fire approximately every 5 years, 25% every 4.1–2.2 years and less than 1% every 2 years on average. Fire return period decreased in relation to an increase in mean annual rainfall. For terrestrial vegetation types, median fire return periods decreased with increasing herbaceous biomass, from forest that did not burn to grasslands that burnt every 2.64 years. Fire was absent from some permanent wetlands but seasonal wetlands burnt every 5.29 years. Grazer biomass above 0.5 animal units ha–1 had a limiting influence on the maximum fire frequency of fire-prone vegetation types. The primary determinant of long-term spatial fire patterns is thus fuel load as determined by mean rainfall, vegetation type, and the effects of grazing herbivores.

scholarly journals Critical loads of sulphur and nitrogen for freshwaters in Great Britain and assessment of deposition reduction requirements with the First-order Acidity Balance (FAB) model

2000 ◽  
Vol 4 (1) ◽  
pp. 125-140 ◽  
Author(s):  
C. Curtis ◽  
T. Allott ◽  
J. Hall ◽  
R. Harriman ◽  
R. Helliwell ◽  
...  
Keyword(s):  
Great Britain ◽  
Water Chemistry ◽  
Critical Load ◽  
Acid Deposition ◽  
Critical Loads ◽  
Freshwater Ecosystems ◽  
Acid Neutralizing Capacity ◽  
First Order ◽  
Fab Model ◽  
S Deposition

Abstract. The critical loads approach is widely used within Europe to assess the impacts of acid deposition on terrestrial and freshwater ecosystems. Recent work in Great Britain has focused on the national application of the First-order Acidity Balance (FAB) model to a freshwaters dataset of 1470 lake and stream water chemistry samples from sites across Britain which were selected to represent the most sensitive water bodies in their corresponding 10 km grid square. A ``Critical Load Function" generated for each site is compared with the deposition load of S and N at the time of water chemistry sampling. The model predicts that when catchment processes reach steady-state with these deposition levels, increases in nitrate leaching will depress acid neutralizing capacity (ANC) below the critical threshold of 0 μeql-1 at more than a quarter of the sites sampled, i.e. the critical load of acid deposition is exceeded at these sites. The critical load exceedances are generally found in upland regions of high deposition where acidification has been previously recognised, but critical loads in large areas of western Scotland are also exceeded where little biological evidence of acidification has yet been found. There is a regional variation in the deposition reduction requirements for protection of the sampled sites. The FAB model indicates that in Scotland, most of the sampled sites could be protected by sufficiently large reductions in S deposition alone. In the English and Welsh uplands, both S and N deposition must be reduced to protect the sites. Current international commitments to reduce S deposition throughout Europe will therefore be insufficient to protect the most sensitive freshwaters in England and Wales. Keywords: critical loads; acidification; nitrate; FAB model; acid deposition

scholarly journals An Icelandic freshwater radiocarbon reservoir effect: Implications for lacustrine 14C chronologies

The Holocene ◽  
2011 ◽  
Vol 21 (7) ◽  
pp. 1073-1080 ◽  
Author(s):  
P.L. Ascough ◽  
G.T. Cook ◽  
H. Hastie ◽  
E. Dunbar ◽  
M.J. Church ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Spatial Variability ◽  
Spatial Variation ◽  
Age Differences ◽  
Trophic Levels ◽  
Data Set ◽  
Reservoir Effect ◽  
Age Correction ◽  
Freshwater System ◽  
Lake Mývatn

A freshwater radiocarbon (14C) reservoir effect (FRE) is a 14C age offset between the atmospheric and freshwater carbon reservoirs. FREs can be on the order of 10 000 14C yr in extreme examples and are a crucial consideration for 14C dating of palaeoenvironmental and archaeological samples. Correction for a FRE may be possible, provided the FRE and the proportion of FRE-affected carbon within a sample can be accurately quantified. However, although such correction is desirable for affected samples, it is essential that such correction is accurate in order to produce useful chronological information. Accuracy of FRE correction can be limited by spatial variation in FRE within a freshwater system, but despite this there is currently a paucity of information to identify and quantify such variability within affected systems. Here we present results of a study that investigates the effects of spatial FRE variation upon dating accuracy within the freshwater system of Lake Mývatn, northern Iceland. A substantial FRE (>10 000 14C yr) has previously been identified in archaeological and modern samples from the region, which shows the potential for considerable spatial variability. The study also assesses the use of δ13C and δ15N in age correction of affected samples. The results show that benthic detritus and organisms at primary trophic levels from locations within the lake are affected by a FRE of at least 3500 14C yr, with clear spatial variation resulting in 14C age differences of up to 7670 14C yr between samples. There is a broad correlation between stable isotope values and FRE within the data set. However, large associated uncertainties currently preclude highly accurate and precise stable isotope-based quantification of the proportion of FRE-affected carbon within archaeological and palaeoenvironmental samples from Mývatn and the surrounding region.

scholarly journals From Quality to Information Quality in Official Statistics

2016 ◽  
Vol 32 (4) ◽  
pp. 867-885 ◽  
Author(s):  
Ron S. Kenett ◽  
Galit Shmueli
Keyword(s):  
Data Analysis ◽  
Information Quality ◽  
Policy Decision ◽  
Summary Statistics ◽  
Official Statistics ◽  
Data Set ◽  
Engineering Statistics ◽  
Statistics Canada ◽  
Concept Of Information

Abstract The term quality of statistical data, developed and used in official statistics and international organizations such as the International Monetary Fund (IMF) and the Organisation for Economic Co-operation and Development (OECD), refers to the usefulness of summary statistics generated by producers of official statistics. Similarly, in the context of survey quality, official agencies such as Eurostat, National Center for Science and Engineering Statistics (NCSES), and Statistics Canada have created dimensions for evaluating the quality of a survey and its ability to report ‘accurate survey data’. The concept of Information Quality, or InfoQ provides a general framework applicable to data analysis in a broader sense than summary statistics: InfoQ is defined as “the potential of a data set to achieve a specific (scientific or practical) goal by using a given empirical analysis method.” It relies on identifying and examining the relationships between four components: the analysis goal, the data, the data analysis, and the utility. The InfoQ framework relies on deconstructing the InfoQ concept into eight dimensions used for InfoQ assessment. In this article, we compare and contrast the InfoQ framework and dimensions with those typically used by statistical agencies. We discuss how the InfoQ approach can support the use of official statistics not only by governments for policy decision making, but also by other stakeholders, such as industry, by integrating official and organizational data.

Empirical comparison of subgroup effects in conventional and individual patient data meta-analyses

2008 ◽  
Vol 24 (03) ◽  
pp. 358-361 ◽  
Author(s):  
Laura Koopman ◽  
Geert J. M. G. van der Heijden ◽  
Arno W. Hoes ◽  
Diederick E. Grobbee ◽  
Maroeska M. Rovers
Keyword(s):  
Individual Patient Data ◽  
Meta Analysis ◽  
Acute Otitis Media ◽  
Patient Data ◽  
Published Data ◽  
Summary Statistics ◽  
Two Stage ◽  
Data Set ◽  
Meta Analyses ◽  
Subgroup Effects

Objectives:Individual patient data (IPD) meta-analyses have been proposed as a major improvement in meta-analytic methods to study subgroup effects. Subgroup effects of conventional and IPD meta-analyses using identical data have not been compared. Our objective is to compare such subgroup effects using the data of six trials (n= 1,643) on the effectiveness of antibiotics in children with acute otitis media (AOM).Methods:Effects (relative risks, risk differences [RD], and their confidence intervals [CI]) of antibiotics in subgroups of children with AOM resulting from (i) conventional meta-analysis using summary statistics derived from published data (CMA), (ii) two-stage approach to IPD meta-analysis using summary statistics derived from IPD (IPDMA-2), and (iii) one-stage approach to IPD meta-analysis where IPD is pooled into a single data set (IPDMA-1) were compared.Results:In the conventional meta-analysis, only two of the six studies were included, because only these reported on relevant subgroup effects. The conventional meta-analysis showed larger (age < 2 years) or smaller (age ≥ 2 years) subgroup effects and wider CIs than both IPD meta-analyses (age < 2 years: RDCMA-21 percent, RDIPDMA-1-16 percent, RDIPDMA-2-15 percent; age ≥2 years: RDCMA-5 percent, RDIPDMA-1-11 percent, RDIPDMA-2-11 percent). The most important reason for these discrepant results is that the two studies included in the conventional meta-analysis reported outcomes that were different both from each other and from the IPD meta-analyses.Conclusions:This empirical example shows that conventional meta-analyses do not allow proper subgroup analyses, whereas IPD meta-analyses produce more accurate subgroup effects. We also found no differences between the one- and two-stage meta-analytic approaches.

scholarly journals The CH-IRP data set: a decade of fortnightly data of δ<sup>2</sup>H and δ<sup>18</sup>O in streamflow and precipitation in Switzerland

2020 ◽  
Author(s):  
Maria Staudinger ◽  
Stefan Seeger ◽  
Barbara Herbstritt ◽  
Michael Stoelzle ◽  
Jan Seibert ◽  
...  
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
Isotope Composition ◽  
Series Data ◽  
Data Repository ◽  
Summary Statistics ◽  
Individual Study ◽  
Data Set ◽  
Flow Pathways

Abstract. The stable isotopes of oxygen and hydrogen, 2H and 18O, provide information on water flow pathways and hydrologic catchment functioning. Here a data set of time series data on precipitation and streamflow isotope composition in Swiss medium-sized catchments, CH-IRP, is presented that is unique in terms of its long-term multi-catchment coverage along an alpine to pre-alpine gradient. The data set comprises fortnightly time series of both δ2H and δ18O as well as Deuterium excess from streamflow for 23 sites in Switzerland, together with summary statistics of the sampling at each station. Furthermore, time series of δ18O and δ2H in precipitation are provided for each catchment derived from interpolated datasets from the NISOT, GNIP and ANIP networks. For each station we compiled relevant metadata describing both the sampling conditions as well as catchment characteristics and climate infomation. Lab standards and errors are provided, and potentially problematic measurements are indicated to help the user decide on the applicability for individual study purposes. For the future, it is planned that the measurements will be continued at 14 stations as a long-term isotopic measurement network and the CH-IRP data set will, thus, be continuously be extended. The data set can be downloaded from data repository zenodo https://doi.org/10.5281/zenodo.3659679 (Staudinger et al., 2020).

scholarly journals The shifting boxplot. A boxplot based on essential summary statistics around the mean.

2010 ◽  
Vol 3 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Fernando Marmolejo-Ramos ◽  
Tian Siva Tian
Keyword(s):  
Interquartile Range ◽  
Summary Statistics ◽  
Scientific Applications ◽  
Data Set ◽  
Report Data ◽  
Graphical Technique ◽  
The Mean

Boxplots are a useful and widely used graphical technique to explore data in order to better understand the information we are working with. Boxplots display the first, second and third quartile as well as the interquartile range and outliers of a data set. The information displayed by the boxplot, and most of its variations, is based on the data’s median. However, much of scientific applications analyse and report data using the mean. In this paper, we propose a variation of the classical boxplot that displays information around the mean. Some information about the median is displayed as well.

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