Drawing Causal Inferences Research Articles

The Sign of the Bias of Unmeasured Confounding

Unmeasured confounding variables are a common problem in drawing causal inferences in observational studies. A theorem is given which in certain circumstances allows the researcher to draw conclusions about the sign of the bias of unmeasured confounding. Specifically, it is possible to determine the sign of the bias when monotonicity relationships hold between the unmeasured confounding variable and the treatment, and between the unmeasured confounding variable and the outcome. Some discussion is given to the conditions under which the theorem applies and the strengths and limitations of using the theorem to assess the sign of the bias of unmeasured confounding.

A different story on “Theory of Mind” deficit in adults with right hemisphere brain damage

Background: Difficulties in social cognition and interaction can characterise adults with unilateral right hemisphere brain damage (RHD). Some pertinent evidence involves their apparently poor reasoning from a “Theory of Mind” perspective, which requires a capacity to attribute thoughts, beliefs, and intentions in order to understand other people's behaviour. Theory of Mind is typically assessed with tasks that induce conflicting mental representations. Prior research with a commonly used text task reported that adults with RHD were less accurate in drawing causal inferences about mental states than at making non‐mental‐state causal inferences from control texts. However, the Theory of Mind and control texts differed in the number and nature of competing discourse entity representations. This stimulus discrepancy, together with the explicit measure of causal inferencing, likely put the adults with RHD at a disadvantage on the Theory of Mind texts. This project was supported in part by grant # DC01820 from the National Institute on Deafness and Other Communicative Disorders. The authors are indebted to Denise Balason, Meghan Capellini, Bethany Peters, Anita Lewis, Sara Byers, and Annie Palaika for their assistance. Aims: This study revisited the question of Theory of Mind deficit in adults with RHD. The aforementioned Theory of Mind texts were used but new control texts were written to address stimulus discrepancies, and causal inferencing was assessed relatively implicitly. Adults with RHD were hypothesised not to display a Theory of Mind deficit under these conditions. Methods & Procedures: The participants were 22 adults with unilateral RHD from cerebrovascular accident, and 38 adults without brain damage. Participants listened to spoken texts that targeted either mental‐state or non‐mental‐state causal inferences. Each text was followed by spoken True/False probe sentences, to gauge target inference comprehension. Both accuracy and RT data were recorded. Data were analysed with mixed, two‐way Analyses of Variance (Group by Text Type). Outcomes & Results: There was a main effect of Text Type in both accuracy and RT analyses, with a performance advantage for the Theory of Mind/mental‐state inference stimuli. The control group was faster at responding, and primed more for the target inferences, than the RHD group. The overall advantage for Theory of Mind texts was traceable to one highly conventional inference: someone tells a white lie to be polite. Particularly poor performance in mental‐state causal inferencing was not related to neglect or lesion site for the group with RHD. Conclusions: With appropriate stimulus controls and a relatively implicit measure of causal inferencing, this study found no “Theory of Mind” deficit for adults with RHD. The utility of the “Theory of Mind” construct is questioned. A better understanding of the social communication difficulties of adults with RHD will enhance clinical management in the future.

Are RCTs the Gold Standard?

The claims of randomized controlled trials (RCTs) to be the gold standard rest on the fact that the ideal RCT is a deductive method: if the assumptions of the test are met, a positive result implies the appropriate causal conclusion. This is a feature that RCTs share with a variety of other methods, which thus have equal claim to being a gold standard. This article describes some of these other deductive methods and also some useful non-deductive methods, including the hypothetico-deductive method. It argues that with all deductive methods, the benefit that the conclusions follow deductively in the ideal case comes with a great cost: narrowness of scope. This is an instance of the familiar trade-off between internal and external validity. RCTs have high internal validity but the formal methodology puts severe constraints on the assumptions a target population must meet to justify exporting a conclusion from the test population to the target. The article reviews one such set of assumptions to show the kind of knowledge required. The overall conclusion is that to draw causal inferences about a target population, which method is best depends case-by-case on what background knowledge we have or can come to obtain. There is no gold standard.

Measuring the effect of food stamps on food insecurity and hunger: research and policy considerations.

The federal government has estimated the prevalence of household "food insecurity" and "food insecurity with hunger" since 1995. Early observers believed that the new measure could be used to assess and improve the Food Stamp Program (FSP). Ten years of research have tempered the initial optimism. The prevalence of food insecurity with hunger (12.3% of all low-income households in 2004) is much higher among food stamp participant households (18.6% in 2004) than among low-income nonparticipant households (10.1% in 2004), due to strong self-selection effects. Households facing greater hardship are more likely to join the program. This article reviews 6 types of nonexperimental research designs that have been used to address the self-selection problem. The results have been inconclusive and the authors have warned against drawing causal inferences from their research. Ethical random-assignment research designs may be required to satisfy the intense policy interest in measuring the antihunger impact of the FSP. The most promising ethical research designs would test the effects of offering eligibility to households that are currently ineligible or offering increased benefits to households that are currently eligible for small benefit amounts.

Factors Associated With Stigma Among Caregivers of Patients With Bipolar Disorder in the STEP-BD Study

Factors Associated With Stigma Among Caregivers of Patients With Bipolar Disorder in the STEP-BD Study

Factors Associated With Stigma Among Caregivers of Patients With Bipolar Disorder in the STEP-BD Study

Little is known about the factors contributing to mental illness stigma among caregivers of people with bipolar disorder. A total of 500 caregivers of patients participating in the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) study were interviewed in a cross-sectional design on measures of stigma, mood, burden, and coping. Relatives and friends with bipolar disorder were assessed on measures of diagnosis and clinical status, determined by a days-well measure derived from psychiatrist ratings of DSM-IV episode status. Because patients' clinical status varied widely, separate models were run for patients who were euthymic for at least three-fourths of the past year (well group) and for those who met criteria for an affective episode for at least one-fourth of the previous year (unwell group). Stepwise multiple regression was used to identify patient, illness, and caregiver characteristics associated with caregiver stigma. In the unwell group, greater mental illness stigma was associated with bipolar I (versus II) disorder, less social support for the caregiver, fewer caregiver social interactions, and being a caregiver of Hispanic descent. In the well group, greater stigma was associated with being a caregiver who is the adult child of a parent with bipolar disorder, who has a college education, who has fewer social interactions, and who cares for a female bipolar patient. Mental illness stigma was found to be prevalent among caregivers of persons with bipolar disorder who have active symptoms as well as for caregivers of those who have remitted symptoms. Stigma is typically associated with factors identifying patients as "different" during symptomatic periods. Research is needed to understand how the stigma experienced by caregivers during stable phases of illness differs from the stigma experienced during patients' illness states.

Case‐Based Research in Family Therapy

Traditionally, case‐based research has not been considered as scientific by many in the field due to the lack of controlled conditions and objectivity. However, case‐study material may be more effective than once believed in educating family therapists. Future implications of the role of case studies in family therapy research are considered, including the manner in which case studies might be designed to be more rigorous so that they can serve as the basis for drawing causal inferences in clinical cases, and at the same time, provide family therapists with useful information to improve their skills. A discussion section highlights the future direction of case‐based research in the family therapy literature and how it may be used as an effective learning tool.

On ideology, causal inference and the reification of statistical methods: Reflections on "Examining instruction, achievement and equity with NAEP mathematics data."

The purpose of this article is to comment on the prior article entitled "Examining Instruction, Achievement and Equity with NAEP mathematics data," by Sarah Theule Lubienski. That article claims that a prior article by the author suffered from three weaknesses: (1) An attempt to justify No Child Left Behind (NCLB); (2) drawing causal inferences from cross-sectional data; (3) and various statistical quibbles. The author responds to the first claim, by indicating that any mention of NCLB was intended purely to make the article relevant to a policy journal; to the second claim, by noting his own reservations about using cross-sectional data to draw causal inferences; and to the third claim by noting potential issues of quantitative methodology in the Lubienski article. He concludes that studies that use advanced statistical methods are often so opaque as to be difficult to compare, and suggests some advantages to the quantitative transparency that comes from the findings of randomly controlled field trials.

Neighbourhood deprivation, school disorder and academic achievement in primary schools in deprived communities in England

There is growing concern about violent behaviour in schools, involving students, staff and/or parents. A survey of 1777 primary schools (for children aged 5 to 11) throughout England, most in areas of social and economic deprivation, found more disorder in neighbourhoods with greater deprivation. More disorder was also observed when there was more school-level disadvantage (e.g. students receiving free meals), larger school size and more children in need of special education services. Despite difficulties in drawing causal inferences from correlational data, the fact that more disorder significantly predicted lower school achievement for students at 7 and 11 in standardized English, mathematics and science assessments even once school characteristics and neighbourhood deprivation were taken into account is judged noteworthy. Potential confounding factors are considered in the discussion.

Does the case study have a future in the psychiatric literature?

Case studies (that is, case-based research) and their status in contemporary psychiatric literature are the main focus of this article. In essence, it evaluates the validity of such research to determine whether or not it will continue to be useful as a viable tool in light of the current emphasis on empirically validated research in the field of psychiatry. Various implications of the role of case studies are considered, including the ways in which the research might be designed to be more rigorous so that it can serve as the basis for drawing causal inferences in clinical cases. A discussion section highlights the future direction of case-based research in the professional literature and how it may be used to best advantage as a learning tool.

Population structure, differential bias and genomic control in a large-scale, case-control association study

The main problems in drawing causal inferences from epidemiological case-control studies are confounding by unmeasured extraneous factors, selection bias and differential misclassification of exposure. In genetics the first of these, in the form of population structure, has dominated recent debate. Population structure explained part of the significant +11.2% inflation of test statistics we observed in an analysis of 6,322 nonsynonymous SNPs in 816 cases of type 1 diabetes and 877 population-based controls from Great Britain. The remainder of the inflation resulted from differential bias in genotype scoring between case and control DNA samples, which originated from two laboratories, causing false-positive associations. To avoid excluding SNPs and losing valuable information, we extended the genomic control method by applying a variable downweighting to each SNP.

Accumulating Evidence for Prenatal Nutritional Origins of Mental Disorders

THE STUDY BY ST CLAIR ET AL 1 IN THIS ISSUE OF JAMA reports an association between prenatal exposure to severe maternal nutritional deficiency and risk for schizophrenia in adulthood. Examination of this question was achieved through strategic use of the Chinese famine of 1959 through 1961 as the fulcrum of their study design. In so doing, these authors afford yet another excellent example, frequent among articles in the annual JAMA theme issue on violence and human rights, of epidemiologists extracting otherwise inaccessible scientific knowledge from the harsh soil of human catastrophe. Susser and Lin were the first to demonstrate this link between severe maternal nutritional deficiency and the offsprings’ risk for schizophrenia. That earlier study, which served as the scientific impetus and analytic model for the current investigation, examined the association between nutrition and schizophrenia using the unique circumstances created by the Dutch Hunger Winter of 1944-1945. In October 1944, the German Army blockaded food supplies to the Western Netherlands as punishment for Dutch involvement in the planned Allied invasion of Europe. Before the blockade, the food supply had been adequate; in May 1945, following the German retreat, it became quickly plentiful again. In the intervening months, however, the Dutch population, particularly in the larger cities, received increasingly meager food rations, a circumstance rendered especially difficult by an unusually harsh winter. Hence, Dutch women who were pregnant in October 1944 and others who conceived in the following months experienced declining food supplies at varying points in gestation. This wartime disaster, occurring in a previously wellnourished industrialized nation, created a natural experimental framework for examining the association of prenatal nutritional deficiency of varying intensity imposed at different points in intrauterine development with risk for postnatal psychiatric disorder in offspring. Analyses of rates of schizophrenia based on case data derived from the Dutch national psychiatric registry implicated early severe prenatal nutritional deficiency in a 2-fold increased risk of schizophrenia overall and in men and women offspring separately. Parallel studies, drawing on results from the medical examinations conducted on 18-year-old Dutch military recruits, documented a 2to 3-fold increased risk for schizoid personality disorder and for antisocial personality disorder, respectively, among persons exposed early in gestation to severe maternal nutritional deficiency. The schizophrenia findings from the Dutch and Chinese famine studies are in remarkable agreement, a consistency that enhances the validity of both investigations. St Clair et al also report a 2-fold increased risk for schizophrenia among individuals prenatally exposed to famine both overall and for each sex separately. Furthermore, the profile of both “epidemics” is entirely analogous although on vastly different temporal and population scales—an abrupt rate increase among individuals prenatally exposed to the famine followed by a rapid return to previous background rates at the close of the nutritional crisis. Of equal importance from the perspective of confidence in drawing causal inferences, the Chinese study successfully addresses several competing explanations for the Dutch findings, noted but not remediable in the studies on the Dutch famine. The nutritional interpretation of the Dutch famine findings was vulnerable to a variety of alternative explanations. Tulip bulbs, consumed at the height of the famine as a food substitute, could have exerted toxic effects on fetal brain development. Hormonal perturbations prompted by the physiological stress of the exceptionally cold winter, some unidentified aspect of urban life under German occupation toward the very end of the war, or the extremely rapid nutritional repletion starting in May 1945—each jointly or separately might have disturbed neuronal maturation. The Chinese replication of the Dutch findings, given the markedly different circumstances, culture, and ethnicity, renders these competing explanations moot or nearly so. During the Chinese famine, food substitutes comprised tree bark and the green algae chlorella, grown at home in vats of urine; the nutritional deprivation did not coincide with unusually harsh winters nor with military occupation by a foreign power.

The Limitations of Experimental Design: A Case Study Involving Monetary Incentive Effects in Laboratory Markets

We replicate an influential study of monetary incentive effects by Jamal and Sunder (1991) to illustrate the difficulties of drawing causal inferences from a treatment manipulation when other features of the experimental design vary simultaneously. We first show that the Jamal and Sunder (1991) conclusions hinge on one of their laboratory market sessions, conducted only within their fixed-pay condition, that is characterized by a thin market and asymmetric supply and demand curves. When we replicate this structure multiple times under both fixed pay and pay tied to performance, our findings do not support Jamal and Sunder’s (1991) conclusion about the incremental effects of performance-based compensation, suggesting that other features varied in that study likely account for their observed difference. Our ceteris paribus replication leaves us unable to offer any generalized conclusions about the effects of monetary incentives in other market structures, but the broader point is to illustrate that experimental designs that attempt to generalize effects by varying multiple features simultaneously can jeopardize the ability to draw causal inferences about the primary treatment manipulation.

Measuring the impacts of community development initiatives: a new application of the adjusted interrupted time-series method.

The authors contribute to the development of empirical methods for measuring the impacts of place-based local development strategies by introducing the adjusted interrupted time-series (AITS) approach. It estimates a more precise counterfactual scenario, thus offering a stronger basis for drawing causal inferences about impacts. The authors applied the AITS approach to three community development initiatives using single-family home prices as the outcome indicator and found that it could measure impacts on both the base level of prices and the rate of price appreciation. The authors also found a situation in which the method appears unreliable, however. The AITS approach benefits from more recurrent data on outcomes during the pre-and post-intervention periods, with an intertemporal pattern that avoids great volatility. The AITS approach to measuring effects of community development initiatives holds strong promise, with caveats.

The Limitations of Experimental Design: A Case Study Involving Monetary Incentive Effects in Laboratory Markets

We replicate an influential study of monetary incentive effects by Jamal and Sunder (1991) to illustrate the difficulties of drawing causal inferences from a treatment manipulation when other features of the experimental design vary simultaneously. We first show that the Jamal and Sunder (1991) conclusions hinge on one of their laboratory market sessions, conducted only within their fixed-pay condition, that is characterized by a thin market and asymmetric supply and demand curves. When we replicate this structure multiple times under both fixed pay and pay tied to performance, our findings do not support Jamal and Sunder's (1991) conclusion about the incremental effects of performance-based compensation, suggesting that other features varied in that study likely account for their observed difference. Our ceteris paribus replication leaves us unable to offer any generalized conclusions about the effects of monetary incentives in other market structures, but the broader point is to illustrate that experimental designs that attempt to generalize effects by varying multiple features simultaneously can jeopardize the ability to draw causal inferences about the primary treatment manipulation.

Sexual Modification Therapies: Ethical Controversies, Philosophical Disputes, and Theological Reflections

Knowing, either by the light of natural reason or by the light of Christian revelation, that homosexuality is a disordered condition is not sufficient for its being ethically permissible to direct self-identified homosexual persons toward just any treatment that aims to modify sexual orientation. For example, such an undertaking would be morally impermissible in cases where the available "treatments" are known to be both futile and potentially damaging to persons undertaking them. I, therefore, introduce this edition of Christian Bioethics by reflecting on (a) the position of homosexuality in our current psychiatric nosology, (b) problems with drawing causal inferences from the outcomes of psychotherapy studies, and (c) the advantages and disadvantages of appealing to traditional categories of sexual orientation in this discussion, all with an eye toward more deeply elucidating core ethical concerns involving the intentional psychotherapeutic modification of sexual orientation.

Genetic testing for sale.

Population-based genetic research has many purposes, one of which is to develop practical applications of prevention and therapy. This obviously includes the possi bility of commercial uses. Although commercialization of genetic testing is not a matter of concern in itself, there is reason to be concerned about premature transfer from research to marketing. We describe 2 examples of a clearly premature use (or misuse) of genetic testing for low-penetrant genes.

The mind's best trick: how we experience conscious will

We often consciously will our own actions. This experience is so profound that it tempts us to believe that our actions are caused by consciousness. It could also be a trick, however – the mind's way of estimating its own apparent authorship by drawing causal inferences about relationships between thoughts and actions. Cognitive, social, and neuropsychological studies of apparent mental causation suggest that experiences of conscious will frequently depart from actual causal processes and so might not reflect direct perceptions of conscious thought causing action.

Traffic safety: ambitious targets and initiatives in Canada and around the world.

This paper is about the general disconnect that we see, both in practice and in literature, between the disciplines of travel demand modeling and causal inference. In this paper, we assert that travel demand modeling should be one of the many fields that focuses on the production of valid causal inferences, and we hypothesize about reasons for the current disconnect between the two bodies of research. Furthermore, we explore the potential benefits of uniting these two disciplines. We consider what travel demand modeling can gain from greater incorporation of techniques and perspectives from the causal inference literatures, and we briefly discuss what the causal inference literature might gain from the work of travel demand modelers. In this paper, we do not attempt to “solve” issues related to the drawing of causal inferences from travel demand models. Instead, we hope to spark a larger discussion both within and between the travel demand modeling and causal inference literatures. In particular, we hope to incite discussion about the necessity of drawing causal inferences in travel demand applications and the methods by which one might credibly do so.

Overrepresentation of Minority Students

The topic of overrepresentation certainly commands attention in the literature on “judgmental categories” of disability (e.g., ‘learning disabilities, mild mental retardation), yet the evidence reported to date bearing on the issue are less than precise. Clearly, the issue is broader than simple overrepresentation, given that far more egregious examples of overrepresentation in Head Start and Chapter I have yet to be criticized, let alone taken to court. In this article the authors distinguish between the percentage of category or program by group and percentage of group in category or program which provide quite different perspectives. Futhermore, the authors caution drawing causal inferences from what are descriptive data relating “race/ethnicity” to “placement in disability category.” Caution is in order because the data reported by OCR represent aggregated data on race/ethnicity from sources that use different approaches to recording a child's race, fail to account for biracial children, and fail to consider the possibility that social class rather than race/ethnicity may be implicated. The second variable considered is placement in state-sactioned disability categories. The variability in rates across states reported in Annual Reports to Congress, coupled with research data demonstrating the lack of decision reliability, raises serious doubts concerning the validity of these designations. Cross-tabulating two categorical variables so fraught with measurement problems compromises any conclusions that might be drawn.