The Bradford Hill considerations on causality: a counterfactual perspective

Stress exposure in intrauterine life is associated with shorter telomere length in young adulthood

Leukocyte telomere length (LTL) is a predictor of age-related disease onset and mortality. The association in adults of psychosocial stress or stress biomarkers with LTL suggests telomere biology may represent a possible underlying mechanism linking stress and health outcomes. It is, however, unknown whether stress exposure in intrauterine life can produce variations in LTL, thereby potentially setting up a long-term trajectory for disease susceptibility. We, therefore, as a first step, tested the hypothesis that stress exposure during intrauterine life is associated with shorter telomeres in adult life after accounting for the effects of other factors on LTL. LTL was assessed in 94 healthy young adults. Forty-five subjects were offspring of mothers who had experienced a severe stressor in the index pregnancy (prenatal stress group; PSG), and 49 subjects were offspring of mothers who had a healthy, uneventful index pregnancy (comparison group; CG). Prenatal stress exposure was a significant predictor of subsequent adult telomere length in the offspring (178-bp difference between prenatal stress and CG; d = 0.41 SD units; P < 0.05). The effect was substantially unchanged after adjusting for potential confounders (subject characteristics, birth weight percentile, and early-life and concurrent stress level), and was more pronounced in women (295-bp difference; d = 0.68 SD units; P < 0.01). To the best of our knowledge, this study provides the first evidence in humans of an association between prenatal stress exposure and subsequent shorter telomere length. This observation may help shed light on an important biological pathway underlying the developmental origins of adult health and disease risk.

26th Hohenheim Consensus Conference, September 11, 2010 Scientific substantiation of health claims: evidence-based nutrition

OBJECTIVE

The objective was to define the term evidence based nutrition on the basis of expert discussions and scientific evidence.

METHODS AND PROCEDURES

The method used is the established Hohenheim Consensus Conference. The term "Hohenheim Consensus Conference" defines conferences dealing with nutrition-related topics. The major aim of the conference is to review the state of the art of a given topic with experts from different areas (basic science, clinicians, epidemiologists, etc.). Based on eight to 12 questions, the experts discuss short answers and try to come to a consensus. A scientifically based text is formulated that justifies the consensus answer. To discuss the requirements for the scientific substantiation of claims, the 26th Hohenheim Consensus Conference gathered the views of many academic experts in the field of nutritional research and asked these experts to address the various aspects of a claims substantiation process and the possibilities and limitations of the different approaches.

RESULTS

The experts spent a day presenting and discussing their views and arrived at several consensus statements that can serve as guidance for bodies performing claims assessments in the framework of regulatory systems.

CONCLUSION

The 26th Hohenheim Consensus Conference addresses some general aspects and describes the current scientific status from the point of view of six case studies to illustrate specific areas of scientific interest: carotenoids and vitamin A in relation to age-related macular degeneration, the quality of carbohydrates (as expressed by the glycemic index) in relation to health and well-being, probiotics in relation to intestinal and immune functions, micronutrient intake and maintenance of normal body functions, and food components with antioxidative properties and health benefits.

Integrating the totality of food and nutrition evidence for public health decision making and communication

The interpretation and integration of epidemiological studies detecting weak associations (RR < 2) with data from other study designs (e.g., animal models and human intervention trials) is both challenging and vital for making science-based dietary recommendations in the nutrition and food safety communities. The 2008 ILSI North America “Decision-Making for Recommendations and Communication Based on Totality of Food-Related Research” workshop provided an overview of epidemiological methods, and case-study examples of how weak associations have been incorporated into decision making for nutritional recommendations. Based on the workshop presentations and dialogue among the participants, three clear strategies were provided for the use of weak associations in informing nutritional recommendations for optimal health. First, enable more effective integration of data from all sources through the use of genetic and nutritional biomarkers; second, minimize the risk of bias and confounding through the adoption of rigorous quality-control standards, greater emphasis on the replication of study results, and better integration of results from independent studies, perhaps using adaptive study designs and Bayesian meta-analysis methods; and third, emphasize more effective and truthful communication to the public about the evolving understanding of the often complex relationship between nutrition, lifestyle, and optimal health.

An overview of case-control study designs and their advantages and disadvantage

Background

Case-control studies are analytical observational research studies which identify cases of subjects with an outcome or disease of interest, match these with appropriate controls without the condition, and then obtain a history of exposure for both groups.

Contents

This article provides an overview of the design, analysis, interpretation, advantages and disadvantages of case-controlled studies. Readers should appreciate the strengths, weaknesses and potential pitfalls of case-control studies when interpreting results and applying them to clinical practice.

Conclusions

Although lower in the research hierarchy than cohort studies and randomized controlled trials, case-control studies may be the only viable research design for investigating rare conditions within a short time period

An overview of cohort study designs and their advantages and disadvantages

Background

Cohort studies are analytical observational research studies which follow groups (cohorts) of subjects forward in time from an exposure to an outcome/s. Rigorous cohort studies provide the best scientific evidence of all the observational research designs.

Contents

This paper provides an overview of the definition, design, analysis, interpretation, advantages and disadvantages of cohort studies. Readers should appreciate the strengths, weaknesses and potential pitfalls of cohort studies when interpreting and applying results to clinical practice.

Conclusions

Cohort study designs should be considered when RCT are not possible or practical for ethical, logistical, or financial reasons. When properly designed and interpreted, links between exposures and outcomes (including an indication of causality) can be made.

Algorithms to predict cerebral malaria in murine models using the SHIRPA protocol

Background

Plasmodium berghei ANKA infection in C57Bl/6 mice induces cerebral malaria (CM), which reproduces, to a large extent, the pathological features of human CM. However, experimental CM incidence is variable (50-100%) and the period of incidence may present a range as wide as 6-12 days post-infection. The poor predictability of which and when infected mice will develop CM can make it difficult to determine the causal relationship of early pathological changes and outcome. With the purpose of contributing to solving these problems, algorithms for CM prediction were built.

Methods

Seventy-eight P. berghei-infected mice were daily evaluated using the primary SHIRPA protocol. Mice were classified as CM+ or CM- according to development of neurological signs on days 6-12 post-infection. Logistic regression was used to build predictive models for CM based on the results of SHIRPA tests and parasitaemia.

Results

The overall CM incidence was 54% occurring on days 6-10. Some algorithms had a very good performance in predicting CM, with the area under the receiver operator characteristic (_auROC) curve ≥ 80% and positive predictive values (PV+) ≥ 95, and correctly predicted time of death due to CM between 24 and 72 hours before development of the neurological syndrome (_auROC = 77-93%; PV+ = 100% using high cut off values). Inclusion of parasitaemia data slightly improved algorithm performance.

Conclusion

These algorithms work with data from a simple, inexpensive, reproducible and fast protocol. Most importantly, they can predict CM development very early, estimate time of death, and might be a valuable tool for research using CM murine models.

Role of acute infection in triggering acute coronary syndromes

Acute coronary syndromes are a leading cause of morbidity and mortality worldwide. The mechanisms underlying the triggering of these events are diverse and include increased coronary and systemic inflammatory activity, dominant prothrombotic conditions, increased biomechanical stress on coronary arteries, variations in the coronary arterial tone, disturbed haemodynamic homoeostasis, and altered myocardial metabolic balance. There is experimental evidence that acute infections can promote the development of acute coronary syndromes, and clinical data strongly support a role for acute infections in triggering these events. In our Review, we summarise the pathogenesis of coronary artery disease and present the evidence linking acute infections with the development of acute coronary syndromes. Greater awareness of this association is likely to encourage research into ways of protecting patients who are at high risk.

Living healthier for longer: comparative effects of three heart-healthy behaviors on life expectancy with and without cardiovascular disease

Background

Non-smoking, having a normal weight and increased levels of physical activity are perhaps the three key factors for preventing cardiovascular disease (CVD). However, the relative effects of these factors on healthy longevity have not been well described. We aimed to calculate and compare the effects of non-smoking, normal weight and physical activity in middle-aged populations on life expectancy with and without cardiovascular disease.

Methods

Using multi-state life tables and data from the Framingham Heart Study (n = 4634) we calculated the effects of three heart healthy behaviours among populations aged 50 years and over on life expectancy with and without cardiovascular disease. For the life table calculations, we used hazard ratios for 3 transitions (No CVD to CVD, no CVD to death, and CVD to death) by health behaviour category, and adjusted for age, sex, and potential confounders.

Results

High levels of physical activity, never smoking (men), and normal weight were each associated with 20-40% lower risks of developing CVD as compared to low physical activity, current smoking and obesity, respectively. Never smoking and high levels of physical activity reduced the risks of dying in those with and without a history of CVD, but normal weight did not. Never-smoking was associated with the largest gains in total life expectancy (4.3 years, men, 4.1 years, women) and CVD-free life expectancy (3.8 and 3.4 years, respectively). High levels of physical activity and normal weight were associated with lesser gains in total life expectancy (3.5 years, men and 3.4 years, women, and 1.3 years, men and 1.0 year women, respectively), and slightly lesser gains in CVD-free life expectancy (3.0 years, men and 3.1 years, women, and 3.1 years men and 2.9 years women, respectively). Normal weight was the only behaviour associated with a reduction in the number of years lived with CVD (1.8 years, men and 1.9 years, women).

Conclusions

Achieving high levels of physical activity, normal weight, and never smoking, are effective ways to prevent cardiovascular disease and to extend total life expectancy and the number of years lived free of CVD. Increasing the prevalence of normal weight could further reduce the time spent with CVD in the population.

Seven mistakes and potential solutions in epidemiology, including a call for a World Council of Epidemiology and Causality

All sciences make mistakes, and epidemiology is no exception. I have chosen 7 illustrative mistakes and derived 7 solutions to avoid them. The mistakes (Roman numerals denoting solutions) are:

1. Failing to provide the context and definitions of study populations. (I Describe the study population in detail)

2. Insufficient attention to evaluation of error. (II Don't pretend error does not exist.)

3. Not demonstrating comparisons are like-for-like. (III Start with detailed comparisons of groups.)

4. Either overstatement or understatement of the case for causality. (IV Never say this design cannot contribute to causality or imply causality is ensured by your design.)

5. Not providing both absolute and relative summary measures. (V Give numbers, rates and comparative measures, and adjust summary measures such as odds ratios appropriately.)

6. In intervention studies not demonstrating general health benefits. (VI Ensure general benefits (mortality/morbidity) before recommending application of cause-specific findings.)

7. Failure to utilise study data to benefit populations. (VII Establish a World Council on Epidemiology to help infer causality from associations and apply the work internationally.)

Analysis of these and other common mistakes is needed to benefit from the increasing discovery of associations that will be multiplying as data mining, linkage, and large-scale scale epidemiology become commonplace.

Strength of evidence relating periodontal disease and atherosclerotic disease

This review assesses the strength of evidence relating periodontal disease and atherosclerotic disease (ischemic heart disease, peripheral arterial disease, and ischemic stroke). Periodontal disease and atherosclerotic disease may be linked causally, or their relationship could be explained, wholly or partially, by common risk factors. Many potential pathways for the relationship have been postulated. This article focuses on evaluating the overall body of evidence, according to the following standard causal inference criteria: strength of association, dose-response relationship, time sequence, consistency, specificity, biologic plausibility, and independence from confounding. Each criterion is reviewed and evaluated against the existing literature. In summary, the overall strength of evidence for causal criteria for the relation between periodontal disease and atherosclerotic disease is as follows: The magnitude and consistency of the association is stronger for ischemic stroke (and is low for ischemic heart disease), some evidence for dose response exists, time sequence has been established with more evidence for stroke, and there is definitely biologic plausibility for all these associations. Independence from confounding is also stronger for ischemic stroke and peripheral arterial disease. Specificity is not established for any of these associations, as there are multiple risk factors for atherosclerotic disease; however, specificity is not considered an important criterion for causality. Because the underlying pathogenesis of atherosclerosis is common across the diseases, it is likely that if additional studies show consistent associations, periodontal disease may be an important independent causal risk factor for atherosclerotic disease, especially for ischemic stroke.

Adverse events following chiropractic care for subjects with neck or low-back pain: do the benefits outweigh the risks?

This synopsis provides an overview of the benign and serious risks associated with chiropractic care for subjects with neck or low-back pain. Most adverse events associated with spinal manipulation are benign and self-limiting. The incidence of severe complications following chiropractic care and manipulation is extremely low. The best evidence suggests that chiropractic care is a useful therapy for subjects with neck or low-back pain for which the risks of serious adverse events should be considered negligible.

Questions on causality and responsibility arising from an outbreak of Pseudomonas aeruginosa infections in Norway

In 2002, Norway experienced a large outbreak of Pseudomonas aeruginosa infections in hospitals with 231 confirmed cases. This fuelled intense public and professional debates on what were the causes and who were responsible. In epidemiology, other sciences, in philosophy and in law there is a long tradition of discussing the concept of causality. We use this outbreak as a case; apply various theories of causality from different disciplines to discuss the roles and responsibilities of some of the parties involved. Mackie's concept of INUS conditions, Hill's nine viewpoints to study association for claiming causation, deterministic and probabilistic ways of reasoning, all shed light on the issues of causality in this outbreak. Moreover, applying legal theories of causation (counterfactual reasoning and the "but-for" test and the NESS test) proved especially useful, but the case also illustrated the weaknesses of the various theories of causation.

We conclude that many factors contributed to causing the outbreak, but that contamination of a medical device in the production facility was the major necessary condition. The reuse of the medical device in hospitals contributed primarily to the size of the outbreak. The unintended error by its producer – and to a minor extent by the hospital practice – was mainly due to non-application of relevant knowledge and skills, and appears to constitute professional negligence. Due to criminal procedure laws and other factors outside the discourse of causality, no one was criminally charged for the outbreak which caused much suffering and shortening the life of at least 34 people.

Better environmental decision making - recent progress and future trends

Recent trends in risk-based decision making are reviewed in relation to novel developments in comparative risk analysis, strategic risk analysis, weight of evidence frameworks, and participative decision making. Delivery of these innovations must take account of organisational capabilities in risk management and the institutional culture that implements decision on risk. We stress the importance of managing risk knowledge within organisations, and emphasise the use of core criteria for effective risk-based decisions by reference to decision process, implementation and the security of strategic added value.

Linking causal concepts, study design, analysis and inference in support of one epidemiology for population health

In this paper, which is dedicated to Dr. Calvin Schwabe, I review the concepts of causation and how they impact on study design, analysis and interpretation of results. Notwithstanding the fact that no observational study can prove causation, there are a number of issues that if addressed sufficiently, can improve the validity and usefulness of our studies. These are elaborated with specific recommendations for the conduct of future observational research. Approaches that have been useful in my teaching and research experience are also described.

Quantifying the effect of a community-based injury prevention program in Queensland using a generalized estimating equation approach

OBJECTIVE

To develop a generalized estimating equation (GEE) model of childhood injury rates to quantify the effectiveness of a community-based injury prevention program implemented in 2 communities in Australia, in order to contribute to the discussion of community-based injury prevention program evaluation.

DESIGN

An ecological study was conducted comparing injury rates in two intervention communities in rural and remote Queensland, Australia, with those of 16 control regions. A model of childhood injury was built using hospitalization injury rate data from 1 July 1991 to 30 June 2005 and 16 social variables. The model was built using GEE analysis and was used to estimate parameters and to test the effectiveness of the intervention.

RESULTS

When social variables were controlled for, the intervention was associated with a decrease of 0.09 injuries/10,000 children aged 0-4 years (95% CI -0.29 to 0.11) in logarithmically transformed injury rates; however, this decrease was not significant (p = 0.36).

CONCLUSIONS

The evaluation methods proposed in this study provide a way of determining the effectiveness of a community-based injury prevention program while considering the effect of baseline differences and secular changes in social variables.

Gold standards in pharmacovigilance: the use of definitive anecdotal reports of adverse drug reactions as pure gold and high-grade ore

Anecdotal reports of adverse drug reactions are generally regarded as being of poor evidential quality. This is especially relevant for postmarketing drug safety surveillance, which relies heavily on spontaneous anecdotal reports. The numerous limitations of spontaneous reports cannot be overemphasised, but there is another side to the story: these datasets also contain anecdotal reports that can be considered to describe definitive adverse reactions, without the need for further formal verification. We have previously defined four categories of such adverse reactions: (i) extracellular or intracellular tissue deposition of the drug or a metabolite; (ii) a specific anatomical location or pattern of injury; (iii) physiological dysfunction or direct tissue damage demonstrable by physicochemical testing; and (iv) infection, as a result of the administration of an infective agent as the therapeutic substance or because of demonstrable contamination. In this article, we discuss the implications of these definitive ('between-the-eyes') adverse effects for pharmacovigilance.

Epidemiological evidence for Mycobacterium avium subspecies paratuberculosis as a cause of Crohn's disease

Mycobacterium avium subspecies paratuberculosis is the causative agent of Johne's disease, a chronic enteritis in ruminants including cattle, sheep, goats, and farmed deer. Recently, this bacterium has received an increasingly wide interest because of a rapidly growing body of scientific evidence which suggests that human infection with this microorganism may be causing some, and possibly all, cases of Crohn's disease. Recent studies have shown that a high percentage of people with Crohn's disease are infected with M. avium subsp. paratuberculosis; whether the association of this bacterium and Crohn's disease is causal or coincidental is not known. Crohn's disease is a gastrointestinal disease in humans with similar histopathological findings to those observed in the paucibacillary form of Johne's disease in cattle. The search for risk factors in Crohn's disease has been frustrating. However, epidemiologists have gathered enough information that points to an association between M. avium subsp. paratuberculosis and Crohn's disease. This paper reviews epidemiological models of disease causation, the major philosophical doctrines about causation, the established epidemiological criteria for causation, and the currently known epidemiological evidence of M. avium subsp. paratuberculosis as a possible cause of Crohn's disease.

Is abuse causally related to urologic symptoms? Results from the Boston Area Community Health (BACH) Survey

OBJECTIVES

We investigated (1) whether sexual, physical, or emotional abuse experienced either as a child or as an adolescent/adult is associated with symptoms of urinary frequency, urgency, and nocturia, and (2) the extent to which the observed association between abuse and urologic symptoms may be causal.

METHODS

Analyses are based on data from the Boston Area Community Health (BACH) survey, a community-based epidemiologic study of many different urologic symptoms and risk factors. BACH used a multistage stratified cluster sample to recruit 5506 adults, aged 30-79 yr (2301 men, 3205 women; 1770 black [African American], 1877 Hispanic, and 1859 white respondents).

RESULTS

The symptoms considered are common, with 33% of BACH respondents reporting urinary frequency, 12% reporting urgency, and 28% reporting nocturia. All three symptoms are positively associated with childhood and adolescent/adult sexual, physical, and emotional abuse (p<0.05), with abuse significantly increasing the odds of urinary frequency by a factor ranging from 1.6 to 1.9, the odds of urgency by a factor from 2.0 to 2.3, and the odds of nocturia by a factor from 1.3 to 1.5.

CONCLUSIONS

Our analyses extend previous work. First, we show a strong association between abuse and urinary frequency, urgency, and nocturia in a community-based random sample. Second, we move beyond discussion of statistical association and find considerable evidence to suggest that the relationship between abuse and these symptoms may be causal.

Periodontitis is characterized by elevated PAI-1 activity

OBJECTIVES

Periodontitis is a chronic infectious disease and has been associated with cardiovascular diseases (CVD). We investigated whether plasma levels of markers of a prothrombotic state were elevated in patients with periodontitis in comparison with healthy controls.

MATERIALS AND METHODS

Untreated patients with moderate (n=53) and severe periodontitis (n=38) and healthy controls (n=39) were recruited. Levels of von Willebrand factor (vWF), prothrombin fragment 1+2 (F1+2), plasminogen activator inhibitor-1 (PAI-1) activity and D-dimer were measured as markers of a prothrombotic state.

RESULTS

The erythrocyte sedimentation rate (ESR), plasma C-reactive protein (CRP) and leucocyte counts (WBC) were significantly higher in patients with periodontitis. No statistically significant difference was found among the three groups for vWF (p=0.264), F1+2 (p=0.295) and D-dimer (p=0.572). However, PAI-1 was clearly elevated in the severe periodontitis group (p=0.001), even after adjusting for potential confounding factors (p(adj)=0.004). Moreover, more patients than controls were having vWF and PAI-1 levels above the respective population medians.

CONCLUSIONS

In periodontitis, elevated levels of PAI-1 activity are observed compared with healthy controls. This may increase the potential for impaired fibrinolysis, a condition that results in a prothrombotic state. We suggest that this state, if left untreated, may contribute to an increased risk for CVD.

Interdisciplinary Rehabilitation in Fibromyalgia and Chronic Back Pain: A Prospective Outcome Study

This study aimed to examine short-term and mid-term course of health, biopsychosocial functional ability, and coping performance of patients with fibromyalgia (FM) or chronic back pain (BP) after participation in a standardized 4-week inpatient, interdisciplinary pain rehabilitation program. In a prospective cohort study, assessments were made by using a set of standardized, well-tested self-rating instruments and other parameters before and after the intervention up to the 6-month follow-up with standardized effect sizes (ES) and comparison to population norms. The effects of improvements in health and coping domains on pain reduction were examined by linear regression modeling. The health of the 65 FM and the 60 BP patients at baseline was far worse than expected from the norms. Improvements included ES up to 1.09 for pain, physical role performance, and mental/affective health dimensions and 0.50 in coping at discharge from the clinic. At the 6-month follow-up, all effects were consistently lower but still up to ES = 0.75. Improvements of FM and BP were equal at discharge but slightly better for the FM's mood scales at the 6-month follow-up. Physical and social function, mood, and coping were significantly associated with pain reduction.

PERSPECTIVE

Inpatient, structured interdisciplinary rehabilitation covering elements of cognitive and operant behavioral therapy, graded activity exercise, and adapted drug therapy revealed moderate to large short-term and mid-term improvements in physical and mental health and in the major coping dimensions as captured by comprehensive and specific assessment.

Challenges in interpreting study results

BACKGROUND

Many studies investigating the relationship between periodontal disease and systemic diseases have been reported; the majority of these have been epidemiologic (or observational) studies. The purpose of this article is to help readers understand the strengths and limitations of epidemiology for the purpose of being better able to interpret these studies.

FINDINGS

Epidemiologic studies include retrospective case-control studies and prospective cohort studies. While these studies cannot prove causality, they can provide strong evidence for and show the strength of an association between a disease and putative causative factors. Randomized controlled trials (RCTs) are used to test therapeutic and preventive measures and can provide presumptive evidence of disease causation in certain circumstances. Each of these study types has limitations that can distort the study results and, therefore, should be considered in study design and analysis.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Epidemiologic studies conducted to date suggest an association between periodontal disease and a number of systemic diseases. However, the strength and nature of this association are not yet clear, because in some cases it might result from confounding by smoking or other variables. Additional well-designed observational studies and future RCTs should increase our understanding of the actual relationship between periodontal and systemic diseases.

Getting causal considerations back on the right track

In their commentary on my paper Phillips and Goodman suggested that counterfactual causality and considerations on causality like those by Bradford Hill are only "guideposts on the road to common sense". I argue that if common sense is understood to mean views that the vast majority of researchers share, Hill's considerations did not lead to common sense in the past--precisely because they are so controversial. If common sense is taken to mean beliefs that are true, then Hill's considerations can only lead to common sense in the simple and well-understood causal systems they apply to. Counterfactuals, however, are largely common sense in the latter meaning.I suggest that the road of scientific endeavour should lead epidemiologic research toward sound strategies that equip researchers with skills to separate causal from non-causal associations with minimal error probabilities. This is undeniably the right direction and the one counterfactual causality leads to. Hill's considerations are merely heuristics with which epidemiologists may or may not find this direction, and they are likely to fail in complex landscapes (causal systems). In such environments, one might easily lose orientation without further aids (e.g., defendable assumptions on biases). Counterfactual causality tells us when and how to apply these heuristics.

Causal criteria and counterfactuals; nothing more (or less) than scientific common sense

Two persistent myths in epidemiology are that we can use a list of "causal criteria" to provide an algorithmic approach to inferring causation and that a modern "counterfactual model" can assist in the same endeavor. We argue that these are neither criteria nor a model, but that lists of causal considerations and formalizations of the counterfactual definition of causation are nevertheless useful tools for promoting scientific thinking. They set us on the path to the common sense of scientific inquiry, including testing hypotheses (really putting them to a test, not just calculating simplistic statistics), responding to the Duhem-Quine problem, and avoiding many common errors. Austin Bradford Hill's famous considerations are thus both over-interpreted by those who would use them as criteria and under-appreciated by those who dismiss them as flawed. Similarly, formalizations of counterfactuals are under-appreciated as lessons in basic scientific thinking. The need for lessons in scientific common sense is great in epidemiology, which is taught largely as an engineering discipline and practiced largely as technical tasks, making attention to core principles of scientific inquiry woefully rare.