G*Power (Erdfelder, Faul, & Buchner, 1996) was designed as a general stand-alone power analysis program for statistical tests commonly used in social and behavioral research. G*Power 3 is a major extension of, and improvement over, the previous versions. It runs on widely used computer platforms (i.e., Windows XP, Windows Vista, and Mac OS X 10.4) and covers many different statistical tests of thet, F, and χ2 test families. In addition, it includes power analyses forz tests and some exact tests. G*Power 3 provides improved effect size calculators and graphic options, supports both distribution-based and design-based input modes, and offers all types of power analyses in which users might be interested. Like its predecessors, G*Power 3 is free.

https://link.springer.com/content/pdf/10.3758/BF03193146.pdf

G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences

This paper presents a review and critique of statistical null hypothesis testing in ecological studies in general, and wildlife studies in particular, and describes an alternative. Our review of Ecology and the Journal of Wildlife Management found the use of null hypothesis testing to be pervasive. The estimated number of P-values appearing within articles of Ecology exceeded 8,000 in 1991 and has exceeded 3,000 in each year since 1984, whereas the estimated number of P-values in the Journal of Wildlife Management exceeded 8,000 in 1997 and has exceeded 3,000 in each year since 1994. We estimated that 47% (SE = 3.9%) of the P-values in the Journal of Wildlife Management lacked estimates of means or effect sizes or even the sign of the difference in means or other parameters. We find that null hypothesis testing is uninformative when no estimates of means or effect size and their precision are given. Contrary to common dogma, tests of statistical null hypotheses have relatively little utility in science and are not a fundamental aspect of the scientific method. We recommend their use be reduced in favor of more informative approaches. Towards this objective, we describe a relatively new paradigm of data analysis based on Kullback-Leibler information. This paradigm is an extension of likelihood theory and, when used correctly, avoids many of the fundamental limitations and common misuses of null hypothesis testing. Information-theoretic methods focus on providing a strength of evidence for an a priori set of alternative hypotheses, rather than a statistical test of a null hypothesis. This paradigm allows the following types of evidence for the alternative hypotheses: the rank of each hypothesis, expressed as a model; an estimate of the formal likelihood of each model, given the data; a measure of precision that incorporates model selection uncertainty; and simple methods to allow the use of the set of alternative models in making, formal inference. We provide an example of the information-theoretic approach using data on the effect of lead on survival in spectacled eider ducks (Somateria fischeri). Regardless of the analysis paradigm used, we strongly recommend inferences based on a priori considerations be clearly separated from those resulting from some form of data dredging.

Null hypothesis testing: problems, prevalence, and an alternative

In many forested ecosystems, the architecture and functional ecology of certain tree species define forest structure and their species-specific traits control ecosystem dynamics. Such foundation tree species are declining throughout the world due to introductions and outbreaks of pests and pathogens, selective removal of individual taxa, and over-harvesting. Through a series of case studies, we show that the loss of foundation tree species changes the local environment on which a variety of other species depend; how this disrupts fundamental ecosystem processes, including rates of decomposition, nutrient fluxes, carbon sequestration, and energy flow; and dramatically alters the dynamics of associated aquatic ecosystems. Forests in which dynamics are controlled by one or a few foundation species appear to be dominated by a small number of strong interactions and may be highly susceptible to alternating between stable states following even small perturbations. The ongoing decline of many foundation species provides a set of important, albeit unfortunate, opportunities to develop the research tools, models, and metrics needed to identify foundation species, anticipate the cascade of immediate, short- and long-term changes in ecosystem structure and function that will follow from their loss, and provide options for remedial conservation and management.

/pdf/loss-of-foundation-species-consequences-for-the-structure-5bng7ar73u.pdf

Loss of foundation species: consequences for the structure and dynamics of forested ecosystems

It is well known that statistical power calculations can be valuable in planning an experiment. There is also a large literature advocating that power calculations be made whenever one performs a statistical test of a hypothesis and one obtains a statistically nonsignificant result. Advocates of such post-experiment power calculations claim the calculations should be used to aid in the interpretation of the experimental results. This approach, which appears in various forms, is fundamentally flawed. We document that the problem is extensive and present arguments to demonstrate the flaw in the logic.

/pdf/the-abuse-of-power-the-pervasive-fallacy-of-power-2pgs8gsae8.pdf

The Abuse of Power: The Pervasive Fallacy of Power Calculations for Data Analysis

Bayesian estimation for 2 groups provides complete distributions of credible values for the effect size, group means and their difference, standard deviations and their difference, and the normality of the data. The method handles outliers. The decision rule can accept the null value (unlike traditional t tests) when certainty in the estimate is high (unlike Bayesian model comparison using Bayes factors). The method also yields precise estimates of statistical power for various research goals. The software and programs are free and run on Macintosh, Windows, and Linux platforms.

/pdf/bayesian-estimation-supersedes-the-t-test-57drp31ai6.pdf

Bayesian Estimation Supersedes the t Test

A guide to sampling freshwater mussel populations

We conducted a comparative study in the Delaware Water Gap National Recreation Area to determine the potential long-term impacts of hemlock forest decline on stream benthic macroinvertebrate assemb...

Influence of eastern hemlock (Tsuga canadensis) forests on aquatic invertebrate assemblages in headwater streams

Intersex, or the presence of characteristics of both sexes, in fishes that are normally gonochoristic has been used as an indicator of exposure to estrogenic compounds. In 2003, during health assessments conducted in response to kills and a high prevalence of skin lesions observed in smallmouth bass Micropterus dolomieu in the South Branch of the Potomac River, the presence of immature oocytes within testes was noted. To evaluate this condition, a severity index (0-4) was developed based on the distribution of oocytes within the testes. Using gonad samples collected from 2003 to 2005, the number of histologic sections needed to accurately detect the condition in mature smallmouth bass was statistically evaluated. The reliability of detection depended on the severity index and the number of sections examined. Examining five transverse sections taken along the length of the gonad resulted in a greater than 90% probability of detecting testicular oocytes when the severity index exceeded 0.5. Using the severity index we compared smallmouth bass collected at selected sites within the South Branch during three seasons in 2004. Seasonal differences in severity and prevalence were observed. The highest prevalence and severity were consistently noted during the prespawn-spawning season, when compared with the postspawn season. In 2005, smallmouth bass were collected at selected out-of-basin sites in West Virginia where fish kills and external skin lesions have not been reported, as well as at sites in the Shenandoah River, Virginia (part of the Potomac drainage), where kills and lesions occurred in 2004-2005. The prevalence of testicular oocytes is discussed in terms of human population and agricultural intensity.

/pdf/intersex-testicular-oocytes-in-smallmouth-bass-from-the-1gtpxtexjn.pdf

Intersex (Testicular Oocytes) in Smallmouth Bass from the Potomac River and Selected Nearby Drainages

Biology.- Limits on the Global Distribution of Horseshoe Crabs (Limulacea): Lessons Learned from Two Lifetimes of Observations: Asia and America.- Horseshoe Crabs - An Ancient Ancestry Revealed.- The Ecological Importance of Horseshoe Crabs in Estuarine and Coastal Communities: A Review and Speculative Summary.- Relationships Between Sandpipers and Horseshoe Crab in Delaware Bay: A Synthesis.- Horseshoe Crabs, Their Eco-biological Status Along the Northeast Coast of India and the Necessity for Ecological Conservation.- American Horseshoe Crabs, Limulus polyphemus, in Mexico: Open Possibilities.- Basic Habitat Requirements of the Extant Species of Horseshoe Crabs (Limulacea).- The Relationship Between Small- and Large-Scale Movements of Horseshoe Crabs in the Great Bay Estuary and Limulus Behavior in the Laboratory.- Ecology of Horseshoe Crabs in Microtidal Lagoons.- Phylogeography, Demographic History, and Reserves Network of Horseshoe Crab, Tachypleus tridentatus, in the South and East China Seaboards.- Genetic Structure of Japanese Populations of Tachypleus tridentatus by mtDNA AT-Rich Region Sequence Analysis.- Reproductive Competition and Sexual Selection in Horseshoe Crabs.- Vision in Horseshoe Crabs.- Sperm Attachment on the Egg of Malaysian King Crab, Carcinoscorpius rotundicauda.- Distribution and Development of Limulus Egg Clusters on Intertidal Beaches in Delaware Bay.- Comparisons in Prosomal Width and Body Weight Among Early Instar Stages of Malaysian Horseshoe Crabs, Carcinoscorpius rotundicauda and Tachypleus gigas in the Laboratory.- Emergence Behavior of Juvenile Tachypleus tridentatus Under Simulated Tidal Conditions in the Laboratory and at Two Different Sediment Temperatures.- Distribution of Juvenile Horseshoe Crabs in Subtidal Habitats of Delaware Bay Using a Suction-Dredge Sampling Device.- Conservation.- History of Horseshoe Crab Harvest on Delaware Bay.- Biomedical Applications of Limulus Amebocyte Lysate.- The Effect of Hemolymph Extraction Volume and Handling Stress on Horseshoe Crab Mortality.- Horseshoe Crabs in Hong Kong: Current Population Status and Human Exploitation.- Comparative Status and Assessment of Limulus polyphemus with Emphasis on the New England and Delaware Bay Populations.- An Integrative Approach to Horseshoe Crab Multiple Use and Sustainability.- Strategies to Conserve and Enhance Sandy Barrier Habitat for Horseshoe Crabs (Limulus polyphemus) on Developed Shorelines in Delaware Bay, United States.- Conservation Program for the Asian Horseshoe Crab Tachypleus tridentatus in Taiwan: Characterizing the Microhabitat of Nursery Grounds and Restoring Spawning Grounds.- The Effects of Water Quality on Horseshoe Crab Embryos and Larvae.- Heavy Metal Concentration in Horseshoe Crab (Carcinoscorpius rotundicauda and Tachypleus gigas) Eggs from Malaysian Coastline.- A Discussion of Horseshoe Crab Management in Five Countries: Taiwan, India, China, United States, and Mexico.- Clinical Evaluation, Common Diseases, and Veterinary Care of the Horseshoe Crab, Limulus polyphemus.- Aquaculture Methods and Early Growth of Juvenile Horseshoe Crabs (Limulus polyphemus).- Larval Culture of Tachypleus gigas and Its Molting Behavior Under Laboratory Conditions.- Diet Composition of Juvenile Horseshoe Crabs: Implications for Growth and Survival of Natural and Cultured Stocks.- Effect of Sediment Type on Growth and Survival of Juvenile Horseshoe Crabs (Tachypleus tridentatus).- The Conservation Network of Horseshoe Crab Tachypleus tridentatus in Taiwan.- The History of Horseshoe Crab Research and Conservation in Japan.- Public Awareness and Community-Based Conservation for the Horseshoe Crab at Saikai National Park in Nagasaki Prefecture, Japan.- Public Participation in Studies on Horseshoe Crab Populations.- Green Eggs and Sand: A Collaborative Effort of Scientists, Teachers, Resource Managers, and Stakeholders in Educating About Limulus polyphemus.- Community Building: An Integrated Approach to Horseshoe Crab Conservation.

Biology and Conservation of Horseshoe Crabs

Power analysis after study completion has been suggested to interpret study results. We present 3 methods of estimating power and discuss their limitations. We use simulation studies to show that estimated power can be biased, extremely variable, and severely bounded. We endorse the practice of computing power to detect a biologically meaningful difference as a tool for study planning but suggest that calculation of confidence intervals on the parameter of interest is the appropriate way to gauge the strength and biological meaning of study results.

David R. Smith

Papers

A guide to sampling freshwater mussel populations

Influence of eastern hemlock (Tsuga canadensis) forests on aquatic invertebrate assemblages in headwater streams

Intersex (Testicular Oocytes) in Smallmouth Bass from the Potomac River and Selected Nearby Drainages

Biology and Conservation of Horseshoe Crabs

Limits of retrospective power analysis