Untested Assumptions Research Articles

How We See Area and Why It Matters.

A large and growing literature examines how we see the visual quantities of number, area, and density. The literature rests on an untested assumption: that our perception of area is veridical. Here, we discuss a systematic distortion of perceived area and its implications for quantity perception more broadly.

Game-Based Social Learning for Socially Sustainable Water Management

An important aspect of the social sustainability of a proposed solution is acceptance by societal stakeholders. Acceptance is determined by the extent to which the solution matches with stakeholder perspectives on the problem and preferred ways to deal with it. Social learning can contribute to the social sustainability of water management strategies by achieving a convergence in perspectives among societal stakeholders. Serious games have proven to be effective in generating this type of social learning outcomes, but the underlying mechanisms are still unclear. This article aims to clarify how a multi-player serious game on river management (Sustainable Delta) supports social learning among participants with initially diverging perspectives. Based on a conceptual framework for game-based social learning, hypotheses and expectations were formulated and tested with quantitative and qualitative analyses of game sessions. Convergence of perspectives was observed in 10 out of 12 gaming sessions, but could not, or could only to a limited extent, be explained by the presumed learning support mechanisms in the game’s design. This underlines the importance of opening up the black box of serious games to determine how and why they work. If this is neglected, there is a clear risk that the design of games will be based on wrong, untested assumptions and will be less effective in supporting social learning and social sustainability.

Genetic markers validate photo-identification and uniqueness of spot patterns in whale sharks

Monitoring the demographics and movement patterns of mobile marine species underpins appropriate management and conservation strategies. Photographic identification of whale sharks Rhincodon typus based on individual variations in spot patterns is a widely used technique for monitoring of populations, but relies on the untested assumptions that these variations in spot patterns are unique to each shark and can be reliably detected using photo-matching software. This study validated the accuracy of photo-identification technique by manually determining the number of photo-identified individuals showing mismatched genetic profiles created for the individuals using 12 microsatellite markers. Results from 154 photographic and genetic identifications of whale sharks were 100% concordant, showing the uniqueness of spot patterns to each shark and high accuracy of the photo-identification technique. Based on these techniques, we observed an annual resighting rate of approximately 10% at Ningaloo Reef, Western Australia, between 2016 and 2018, showing evidence that variations in spot patterns did not change over a time scale of years. Our study shows that the photographic identification technique provides a reliable means to recognise individuals and monitor whale sharks through time.

A Bayesian semiparametric approach for inference on the population partly conditional mean from longitudinal data with dropout.

Studies of memory trajectories using longitudinal data often result in highly nonrepresentative samples due to selective study enrollment and attrition. An additional bias comes from practice effects that result in improved or maintained performance due to familiarity with test content or context. These challenges may bias study findings and severely distort the ability to generalize to the target population. In this study, we propose an approach for estimating the finite population mean of a longitudinal outcome conditioning on being alive at a specific time point. We develop a flexible Bayesian semiparametric predictive estimator for population inference when longitudinal auxiliary information is known for the target population. We evaluate the sensitivity of the results to untestable assumptions and further compare our approach to other methods used for population inference in a simulation study. The proposed approach is motivated by 15-year longitudinal data from the Betula longitudinal cohort study. We apply our approach to estimate lifespan trajectories in episodic memory, with the aim to generalize findings to a target population.

Gardens of the Coromandel Coast: Landscape Considerations of Commercial Agriculture in Tamil Nadu, South India

The plantation as a fusion of rural industry and commercial agriculture has become a shorthand for the the intensification of land-use, circulation of commodities, and the organization of labor concomitant with the modern world. While not the only place where plantations existed, the Atlantic is the context in which most archaeological research has taken place leaving untested certain assumptions about the development of the plantation. and the regions which informed its varied materializations in the modern world. By extending the the methods and approaches employed by archaeologists studying plantations to South India, we decenter plantation narratives and show how Indian Ocean commercial agriculture and rural industry also enabled the modern world. This article reports on results from the first phase of the Colonial Tharangambadi Archaeological Survey (CTAS). The goal of CTAS was to document changing settlement patterns, settlement organization, and material assemblage through a systematic landscape survey in the former Danish colonial enclave, Tranquebar (Tharangambadi). Specifically, we documented one South Indian settlement formation devoted to commercial agriculture called “gardens,” which has origins in the sixth century CE, or earlier, and how they were used outside the town’s walls in the eighteenth and nineteenth centuries. We argue that from historically distinctive agrarian facilities geared to commercial production, these plantation-like rural industries developed quite broadly using vulnerable labor to produce plant commodities in high volume for international markets. The particularities of plantation studies are enriched by considerations of parallel developments under similar conditions, as illustrated by India’s lesser-known Danish colony.

Commentary: Using potential outcomes causal methods to assess whether reductions in PM2.5 result in decreased mortality

Causal inference regarding exposures to ambient fine particulate matter (PM2.5) and mortality estimated from observational studies is limited by confounding, among other factors. In light of a variety of causal inference frameworks and methods that have been developed over the past century to specifically quantify causal effects, three research teams were selected in 2016 to evaluate the causality of PM2.5-mortality association among Medicare beneficiaries, using their own selections of causal inference methods and study designs but the same data sources. With a particular focus on controlling for unmeasured confounding, two research teams adopted an instrumental variables approach under a quasi-experiment or natural experiment study design, whereas one team adopted a structural nested mean model under the traditional cohort study design. All three research teams reported results supporting an estimated counterfactual causal relationship between ambient PM2.5 and all-cause mortality, and their estimated causal relationships are largely of similar magnitudes to recent epidemiological studies based on regression analyses with omitted potential confounders. The causal methods used by all three research teams were built upon the potential outcomes framework. This framework has marked conceptual advantages over regression-based methods in addressing confounding and yielding unbiased estimates of average treatment effect in observational epidemiological studies. However, potential violations of the unverifiable assumptions underlying each causal method leave the results from all three studies subject to biases. We also note that the studies are not immune to some other common sources of bias, including exposure measurement errors, ecological study design, model uncertainty and specification errors, and irrelevant exposure windows, that can undermine the validity of causal inferences in observational studies. As a result, despite some apparent consistency of study results from the three research teams with the wider epidemiological literature on PM2.5-mortality statistical associations, caution seems warranted in drawing causal conclusions from the results. A possible way forward is to improve study design and reduce dependence of conclusions on untested assumptions by complementing potential outcomes methods with structural causal modeling and information-theoretic methods that emphasize empirically tested and validated relationships.

Does parental education influence child educational outcomes? A developmental analysis in a full-population sample and adoptee design.

Children's educational outcomes are strongly correlated with their parents' educational attainment. This finding is often attributed to the family environment-assuming, for instance, that parents' behavior and resources affect their children's educational outcomes. However, such inferences of a causal role of the family environment depend on the largely untested assumption that such relationships do not simply reflect genes shared between parent and child. We examine this assumption with an adoptee design in full-population cohorts from Danish administrative data. We test whether parental education predicts children's educational outcomes in both biological and adopted children, looking at four components of the child's educational development: (I) the child's conscientiousness during compulsory schooling, (II) academic performance in those same years, (III) enrollment in academically challenging high schools, and (IV) graduation success. Parental education was a substantial predictor of each of these child outcomes in the full population. However, little intergenerational correlation in education was observed in the absence of genetic similarity between parent and child-that is, among adoptees. Further analysis showed that what links adoptive parents' education did have with later-occurring components such as educational attainment (IV) and enrollment (III) appeared to be largely attributable to effects identifiable earlier in development, namely early academic performance (II). The primary nongenetic mechanisms by which education is transmitted across generations may thus have their effects on children early in their educational development, even as the consequences of those early effects persist throughout the child's educational development. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Is attentional discounting in value-based decision making magnitude sensitive?

ABSTRACT Choices in value-based decision making are affected by the magnitude of the alternatives (i.e. the summed values of the options). Magnitude sensitivity has been instrumental in discriminating between computational models of choice. Smith and Krajbich [(2019a). Gaze amplifies value in decision making. Psychological Science, 30(1), 116–128. https://doi.org/10.1177/0956797618810521] have shown that the attentional drift-diffusion model (aDDM) can account for magnitude sensitivity. This is because the discount parameter on the value of the nonfixated alternative ensures faster choices for high-magnitude alternatives, even in the case of high-magnitude equal alternatives compared to low-magnitude equal alternatives. Their result highlights the importance of visual fixations as a mechanism for magnitude sensitivity. This rationale relies on the untested assumption that the discount parameter is constant across magnitude levels. However, the discount parameter could vary as a function of the magnitude of the alternatives in unpredicted ways; this would suggest that the ability of the aDDM to account for magnitude sensitivity has been misinterpreted by previous research. Here, we reanalyse previous datasets and we directly test whether attentional discounting scales with the magnitude of the alternatives. Our analyses show that attentional discounting does not vary with magnitude. This result further strengthens the aDDM and the role that visual fixations could play as an explanation of magnitude sensitivity.

Generation of ultrashort keV Ar+ ion pulses via femtosecond laser photoionization

Ion beams with energies in the keV regime are widely utilized in solid-state physics, but the ultrafast dynamics triggered by an ion impact onto a solid surface is to date exclusively accessible via simulations based on many untested assumptions and model parameters. A possible experimental access rests on the availability of a laser-synchronized ion source delivering sufficiently short ion pulses for time resolved pump–probe experiments. Here, we demonstrate a new miniaturized ion optical bunching setup for the creation of rare gas ion pulses using strong-field femtosecond laser photoionization. Neutral Ar gas atoms at room temperature are intercepted by a 50 fs, 800 nm laser pulse focused to ∼10 μm spot size. We demonstrate the generation of monoenergetic 2 keV Ar+ ion pulses with 180 ps duration (FWHM) at laser peak intensities around 1014 W cm−2 and of multiply charged Ar q+ ions (q = 1–5) at higher laser intensities. The results are in good agreement with detailed ion trajectory simulations, which show that the temporal resolution is essentially limited by the initial (thermal) velocity spread of the generated photo-ions, indicating the possibility to achieve even better time resolution by cooling the gas prior to ionization.

A novel estimand to adjust for rescue treatment inrandomized clinical trials.

The interpretation of randomized clinical trial results is often complicated by intercurrent events. For instance, rescue medication is sometimes given to patients in response to worsening of their disease, either in addition to the randomized treatment or in its place. The use of such medication complicates the interpretation of the intention-to-treat analysis. In view of this, we propose a novel estimand defined as the intention-to-treat effect that would have been observed, had patients on the active arm been switched to rescue medication if and only if they would have been switched when randomized to control. This enables us to disentangle the treatment effect from the effect of rescue medication on a patient's outcome, while tempering the strong extrapolations that are typically needed when inferring what the intention-to-treat effect would have been in the absence of rescue medication. We propose a novel inverse probability weighting method for estimating this effect in settings where the decision to initiate rescue medication is made at one prespecified time point. This estimator relies on specific untestable assumptions, in view of which we propose a sensitivity analysis. We use the method for the analysis of a clinical trial conducted by Janssen Pharmaceuticals, in which patients with type 2 diabetes mellitus can switch to rescue medication for ethical reasons. Monte Carlo simulations confirm that the proposed estimator is unbiased in moderate sample sizes.

Canadian identity attenuates the negative impact of familial rejection on psychological distress

Bicultural individuals generally maintain their heritage cultures and live in accordance with mainstream culture with relative ease. However, when the two cultures hold incompatible values, beliefs, and social norms over what is considered appropriate, bicultural individuals may face unique challenges. One such challenge is potentially experiencing rejection from their families for transgressing their heritage cultural norms, which can cause psychological distress. The present study explored the association of familial rejection for transgressing heritage cultural norms and psychological distress in situations where those norms are incompatible with mainstream Canadian norms, and the role that Canadian group identification plays. Results revealed that familial rejection for transgressing heritage cultural norms may be associated with psychological distress; however, that association can be attenuated for those who strongly identify as Canadian. Results of the present study provide empirical support for the widely held but untested assumption that bicultural individuals’ experiences of familial rejection for transgressing heritage cultural norms is associated with psychological distress. Additionally, results of the present study suggest that Canadian group identification can assist bicultural Canadians to better cope when their familial relationships are threatened as a result of their heritage cultural norm transgressions.

High‐density camera trap grid reveals lack of consistency in detection and capture rates across space and time

AbstractCounts of independent photo events from camera traps are commonly used to make inference about species occupancy, the density of unmarked populations, and the relative abundance of species across time and space. These applications rest on the untested assumption that data collected from individual cameras are representative of the landscape location in which they are placed, and that nearby cameras would record similar data when any additional micro‐site differences are accounted for. We established a high‐density camera trapping grid (100 × 100 m; 27 cameras) in Virginia, USA, to explicitly test these assumptions, investigating variation in capture rates and detection probabilities for a range of terrestrial mammals during four 2‐month seasonal surveys. Despite controlling for numerous habitat and placement factors, we documented, across all 5 focal species, large ranges and coefficients of variation in both capture rate and detection probabilities, which were similar to those seen across 2 sets of independent forest sampling sites from a larger, more typical camera trap sampling design. We also documented a lack of spatial autocorrelation in capture rate at any distance. Measured local covariates relevant to the camera viewshed (stem density, camera height, log presence, effective detection distance [EDD], total dbh of oak trees) rarely explained any significant portion of observed variation in capture rates or detection probabilities across the grid. The influence of EDD, measured here for the first time for individual camera stations, was inconsistently important and varied in direction of effect depending on species and season. Our study indicates single‐camera stations may fail to sample animal presence and frequency of use in a robust and repeatable way, primarily resulting from the influence of both idiosyncrasies in animal movement and measured and unknown micro‐site characteristics. We recommend spatial replication within sites (e.g., small‐scale shifting of cameras or use of multiple stations) should be considered to minimize impacts of relevant micro‐site characteristics, some of which may be difficult to identify.

Registered Report: Testing Ideological Asymmetries in Measurement Invariance.

People with different ideological identities differ in their values, personality, affect, and psychological motivations. These differences are observed on measures of practical and clinical importance and these differences are the central node tying together theories about the psychology of political ideology; however, they rest on a critical untested assumption: The measures are invariant across ideological groups. Here, we test this assumption across 28 constructs in data from the United States and the Netherlands. Measures are not invariant across ideological divisions. At the same time, estimates of ideological similarities and differences are largely similar before and after correcting for measurement noninvariance. This may give us increased confidence in the results from this research area, while simultaneously highlighting that some instance of noninvariance did change conclusions and that individual items are not always comparable across political groups.

Whole plastomes are not enough: phylogenomic and morphometric exploration at multiple demographic levels of the bee orchid clade Ophrys sect. Sphegodes.

Plastid sequences have long dominated phylogeny reconstruction at all time depths, predicated on a usually untested assumption that they accurately represent the evolutionary histories of phenotypically circumscribed species. We combined detailed in situ morphometrics (124 plants) and whole-plastome sequencing through genome skimming (71 plants) in order to better understand species-level diversity and speciation in arguably the most challenging monophyletic group within the taxonomically controversial, pseudo-copulatory bee orchid genus Ophrys. Using trees and ordinations, we interpreted the data at four nested demographic levels-macrospecies, mesospecies, microspecies, and local population-seeking the optimal level for bona fide species. Neither morphological nor molecular discontinuities are evident at any level below macrospecies, the observed overlap among taxa suggesting that both mesospecies and microspecies reflect arbitrary division of a continuum of variation. Plastomes represent geographic location more strongly than taxonomic assignment and correlate poorly with morphology, suggesting widespread plastid capture and possibly post-glacial expansion from multiple southern refugia. As they are rarely directly involved in the speciation process, plastomes depend on extinction of intermediate lineages to provide phylogenetic signal and so cannot adequately document evolutionary radiations. The popular 'ethological' evolutionary model recognizes as numerous 'ecological species' (microspecies) lineages perceived as actively diverging as a result of density-dependent selection on very few features that immediately dictate extreme pollinator specificity. However, it is assumed rather than demonstrated that the many microspecies are genuinely diverging. We conversely envisage a complex four-dimensional reticulate network of lineages, generated locally and transiently through a wide spectrum of mechanisms, but each unlikely to maintain an independent evolutionary trajectory long enough to genuinely speciate by escaping ongoing gene flow. The frequent but localized microevolution that characterizes the Ophrys sphegodes complex is often convergent and rarely leads to macroevolution. Choosing between the contrasting 'discontinuity' and 'ethology' models will require next-generation sequencing of nuclear genomes plus ordination of corresponding morphometric matrices, seeking the crucial distinction between retained ancestral polymorphism-consistent with lineage divergence-and polymorphisms reflecting gene flow through 'hybridization'-more consistent with lineage convergence.

Exploring Heterogeneity in Histology-Independent Technologies and the Implications for Cost-Effectiveness.

BackgroundThe National Institute for Health and Care Excellence and a number of international health technology assessment agencies have recently undertaken appraisals of histology-independent technologies (HITs). A strong and untested assumption inherent in the submissions included identical clinical response across all tumour histologies, including new histologies unrepresented in the trial. Challenging this assumption and exploring the potential for heterogeneity has the potential to impact upon cost-effectiveness.MethodUsing published response data for a HIT, a Bayesian hierarchical model (BHM) was used to identify heterogeneity in response and to estimate the probability of response for each histology included in single-arm studies, which informed the submission for the HIT, larotrectinib. The probability of response for a new histology was estimated. Results were inputted into a simplified response-based economic model using hypothetical parameters. Histology-independent and histology-specific incremental cost-effectiveness ratios accounting for heterogeneity were generated.ResultsThe results of the BHM show considerable heterogeneity in response rates across histologies. The predicted probability of response estimated by the BHM is 60.9% (95% credible interval 16.0; 91.8%), lower than the naively pooled probability of 74.5%. A mean response probability of 56.9% (0.2; 99.9%) is predicted for an unrepresented histology. Based on the economic analysis, the probability of the hypothetical HIT being cost-effective under the assumption of identical response is 78%. Allowing for heterogeneity, the probability of various approval decisions being cost-effective ranges from 93% to 11%.ConclusionsCentral to the challenge of reimbursement of HITs is the potential for heterogeneity. This study illustrates how heterogeneity in clinical effectiveness can result in highly variable and uncertain estimates of cost-effectiveness. This analysis can help improve understanding of the consequences of histology-independent versus histology-specific decisions.

Can the EHT M87 results be used to test general relativity?

No. All theoretical predictions for the observational appearance of an accreting supermassive black hole, as measured interferometrically by a sparse Earth-sized array at current observation frequencies, are sensitive to many untested assumptions about accretion flow and emission physics. There is no way to distinguish a violation of general relativity (GR) from the much more likely scenario that the relevant "gastrophysical" assumptions simply do not hold. Tests of GR will become possible with longer interferometric baselines (likely requiring a space mission) that reach the resolution where astrophysics-independent predictions of the theory become observable.

The Learning Curve: Revisiting the Assumption of Linear Growth during the School Year

Important educational policy decisions, like whether to shorten or extend the school year, often require accurate estimates of how much students learn during the year. Yet, related research relies on a mostly untested assumption: that growth in achievement is linear throughout the entire school year. We examine this assumption using a dataset containing math and reading test scores for over seven million students in kindergarten through 8th grade across the fall, winter, and spring of the 2017–18 school year. Our results indicate that assuming linear within-year growth is often not justified, particularly in reading. Implications for investments in extending the school year, summer learning loss, and the development of racial/ethnic achievement gaps are discussed.

Foreign Policy Revisionism in the Era of COVID-19: Theory and Evidence from Chinese Public Opinion

Political commentary in the era of COVID-19 often takes for granted that the pandemic will transform China’s approach to great-power competition. But implicit in this concern are untested assumptions about the ways in which the pandemic is shaping widespread foreign policy attitudes within America’s foremost geopolitical rival. This study uses original public opinion surveys fielded in China during the first six months of the global pandemic to evaluate these assumptions. We find that ordinary Chinese citizens today are conspicuously optimistic about China’s future position in the global balance of power, and that this optimism corresponds well with the widespread perception that the COVID-19 pandemic is accelerating China’s rise relative to the United States. And crucially, “COVID-19 optimism” reliably predicts increased support for a wide range of revisionist foreign policies, including the use of force against the U.S. and its allies as well as the pursuit of regional hegemony in the Asia-Pacific. That said, there is also evidence that public support for revisionist policies is qualified in important ways. Overall, our findings suggest that the perceived impact of the COVID-19 pandemic can function as a heuristic that profoundly shapes America’s reputation for power abroad.

The perils of untested assumptions in theory testing: A reply to Patrick et al. (2020).

We respond to a critique by Patrick et al. (2020) of our recent study (Roy et al., 2020) that raised questions regarding the three-factor model of the Triarchic Psychopathy Measure (TriPM). Roy et al. demonstrated that a replicable model involving seven unidimensional factors accounted for the TriPM items across North American and European general population samples, as well as European male offenders. Despite having access to large TriPM datasets, the Patrick et al. critique relied on tangential analyses of general personality traits, using a single college sample with TriPM data as supplemental. Thus, Patrick et al. ignored findings highlighting multidimensional TriPM scales and the uncertainty they introduce with respect to the larger nomological network of psychopathy. In our reply, we demonstrate additional problems with the three-factor TriPM model and show that the seven-factor model out-performs the three-factor model in predicting correlates of psychopathy. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Quantifying capital versus income breeding: New promise with stable isotope measurements of individual amino acids.

Capital breeders accumulate nutrients prior to egg development, then use these stores to support offspring development. In contrast, income breeders rely on local nutrients consumed contemporaneously with offspring development. Understanding such nutrient allocations is critical to assessing life-history strategies and habitat use. Despite the contrast between these strategies, it remains challenging to trace nutrients from endogenous stores or exogenous food intake into offspring. Here, we tested a new solution to this problem. Using tissue samples collected opportunistically from wild emperor penguins Aptenodytes forsteri, which exemplify capital breeding, we hypothesized that the stable carbon (δ13 C) and nitrogen (δ15 N) isotope values of individual amino acids (AAs) in endogenous stores (e.g. muscle) and in egg yolk and albumen reflect the nutrient sourcing that distinguishes capital versus income breeding. Unlike other methods, this approach does not require untested assumptions or diet sampling. We found that over half of essential AAs had δ13 C values that did not differ between muscle and yolk or albumen, suggesting that most of these AAs were directly routed from muscle into eggs. In contrast, almost all non-essential AAs differed in δ13 C values between muscle and yolk or between muscle and albumen, suggesting de novo synthesis. Over half of AAs that have labile nitrogen atoms (i.e. 'trophic' AA) had higher δ15 N values in yolk and albumen than in muscle, suggesting that they were transaminated during their routing into egg tissue. This effect was smaller for AAs with less labile nitrogen atoms (i.e. 'source' AA). Our results indicate that the δ15 N offset between trophic-source AAs (Δ15 Ntrophic-source ) may provide an index of the extent of capital breeding. The value of emperor penguin Δ15 NPro-Phe was higher in yolk and albumen than in muscle, reflecting the mobilization of endogenous stores; in comparison, the value of Δ15 NPro-Phe was similar across muscle and egg tissue in previously published data for income-breeding herring gulls Larus argentatus smithsonianus. Our results provide a quantitative basis for using AA δ13 C and δ15 N, and isotopic offsets among AAs (e.g. Δ15 NPro-Phe ), to explore the allocation of endogenous versus exogenous nutrients across the capital versus income spectrum of avian reproduction.