Upward Bias Research Articles

Determining Distinct Suicide Attempts From Recurrent Electronic Health Record Codes: Classification Study.

Prior suicide attempts are a relatively strong risk factor for future suicide attempts. There is growing interest in using longitudinal electronic health record (EHR) data to derive statistical risk prediction models for future suicide attempts and other suicidal behavior outcomes. However, model performance may be inflated by a largely unrecognized form of "data leakage" during model training: diagnostic codes for suicide attempt outcomes may refer to prior attempts that are also included in the model as predictors. We aimed to develop an automated rule for determining when documented suicide attempt diagnostic codes identify distinct suicide attempt events. From a large health care system's EHR, we randomly sampled suicide attempt codes for 300 patients with at least one pair of suicide attempt codes documented at least one but no more than 90 days apart. Supervised chart reviewers assigned the clinical settings (ie, emergency department [ED] versus non-ED), methods of suicide attempt, and intercode interval (number of days). The probability (or positive predictive value) that the second suicide attempt code in a given pair of codes referred to a distinct suicide attempt event from its preceding suicide attempt code was calculated by clinical setting, method, and intercode interval. Of 1015 code pairs reviewed, 835 (82.3%) were nonindependent (ie, the 2 codes referred to the same suicide attempt event). When the second code in a pair was documented in a clinical setting other than the ED, it represented a distinct suicide attempt 3.3% of the time. The more time elapsed between codes, the more likely the second code in a pair referred to a distinct suicide attempt event from its preceding code. Code pairs in which the second suicide attempt code was assigned in an ED at least 5 days after its preceding suicide attempt code had a positive predictive value of 0.90. EHR-based suicide risk prediction models that include International Classification of Diseases codes for prior suicide attempts as a predictor may be highly susceptible to bias due to data leakage in model training. We derived a simple rule to distinguish codes that reflect new, independent suicide attempts: suicide attempt codes documented in an ED setting at least 5 days after a preceding suicide attempt code can be confidently treated as new events in EHR-based suicide risk prediction models. This rule has the potential to minimize upward bias in model performance when prior suicide attempts are included as predictors in EHR-based suicide risk prediction models.

A method to evaluate the rank condition for CCE estimators

We develop a binary classifier to evaluate whether the rank condition (RC) is satisfied or not for the Common Correlated Effects (CCE) estimator. The RC postulates that the number of unobserved factors, m, is not larger than the rank of the unobserved matrix of average factor loadings, ϱ. When this condition fails, the CCE estimator is inconsistent, in general. Despite its importance, to date this rank condition could not be verified. The difficulty lies in the fact that factor loadings are unobserved, such that ϱ cannot be directly determined. The key insight in this article is that ϱ can be consistently estimated with existing techniques through the matrix of cross-sectional averages of the data. Similarly, m can be estimated consistently from the data using existing methods. Thus, a binary classifier, constructed by comparing estimates of m and ϱ, correctly determines whether the RC is satisfied or not as . We illustrate the practical relevance of testing the RC by studying the effect of the Dodd-Frank Act on bank profitability. The RC classifier reveals that the rank condition fails for a subperiod of the sample, in which case the estimated effect of bank size on profitability appears to be biased upwards.

On the persistence of near-surface temperature dynamics in a warming world.

We consider issues related to the effect of climate change on the persistence of (trend-corrected) temperatures using global gridded data for both land and oceans. We first discuss how the presence of trends and additive noise affects inference about persistence. Ignoring a trend induces an upward bias, while not accounting for noise induces a downward bias. We show that the increase in persistence in the commonly used Warm Spell Duration Index is simply an artifact of increasing temperatures. To purge the impact of both trends and noise, we adopt a simple state-space model. Of separate interest, we document a much larger noise component for land than for oceans. The estimates of the persistence are much larger for oceans than for land. Inspection of the estimates across various subsamples and the application of tests for structural changes suggest the same pattern of persistence for both land and oceans across time, with few minor exceptions. Hence, our results show that surface temperature persistence has remained constant during the observed period.

Genotype imputation accuracy and the quality metrics of the minor ancestry in multi-ancestry reference panels.

Large-scale imputation reference panels are currently available and have contributed to efficient genome-wide association studies through genotype imputation. However, whether large-size multi-ancestry or small-size population-specific reference panels are the optimal choices for under-represented populations continues to be debated. We imputed genotypes of East Asian (180k Japanese) subjects using the Trans-Omics for Precision Medicine reference panel and found that the standard imputation quality metric (Rsq) overestimated dosage r2 (squared correlation between imputed dosage and true genotype) particularly in marginal-quality bins. Variance component analysis of Rsq revealed that the increased imputed-genotype certainty (dosages closer to 0, 1 or 2) caused upward bias, indicating some systemic bias in the imputation. Through systematic simulations using different template switching rates (θvalue) in the hidden Markov model, we revealed that the lower θ value increased the imputed-genotype certainty and Rsq; however, dosage r2 was insensitive to the θ value, thereby causing a deviation. In simulated reference panels with different sizes and ancestral diversities, the θ value estimates from Minimac decreased with the size of a single ancestry and increased with the ancestral diversity. Thus, Rsq could be deviated from dosage r2 for a subpopulation in the multi-ancestry panel, and the deviation represents different imputed-dosage distributions. Finally, despite the impact of the θ value, distant ancestries in the reference panel contributed only a few additional variants passing a predefined Rsq threshold. We conclude that the θ value substantially impacts the imputed dosage and the imputation quality metric value.

Does risk matter more in recessions than in expansions? Implications for monetary policy

We employ a nonlinear vector autoregression and a non-recursive identification strategy to show that an equal-sized uncertainty shock generates a larger contraction in real activity when growth is low (as in recessions) than when growth is high (as in expansions). An estimated New Keynesian model with recursive preferences replicates these state-contingent responses when approximated to third order around its risky steady state due to a stronger upward nominal pricing bias in recessions than in expansions. Empirical evidence supports this state-contingent channel, and we show that it can greatly reduce the ability of systematic monetary policy to stabilize output during recessions.

Uncovered interest rate, overshooting, and predictability reversal puzzles in an emerging economy

By using realized and survey-based expected exchange rate data, the paper presents five key findings regarding the Uncovered Interest rate Parity (UIP) and related puzzles in an Emerging Market (EM). First, Fama regressions, when not accounting for shifts in the UIP relationship, yield slopes that are statistically identical to one, irrespective of whether survey-based expected exchange rates or realized exchange rates are used. Second, caution is necessary however, as our analysis identifies three distinct sub-periods within each exchange rate measure, each exhibiting varying levels of puzzling behavior. Third, under realized exchange rates, expectation errors can introduce both downward and upward biases or no bias at all, depending on the sub-period. On the other hand, currency risk premiums consistently lead to a downward bias. Under expected exchange rates, currency risk premiums continue to exert a downward bias at varying degrees across sub-periods. Fourth, responses to interest rate differential shocks by expectation errors are pivotal in inducing both downward and upward biases or removing biases altogether when utilizing realized exchange rate data. Fifth, evidence concerning overshooting and reversal puzzles, as well as their link to the UIP puzzle, varies depending on the specific sub-period and the choice of exchange rate measurement, making it more intricate than the previous literature has documented.

39 Does Pseudoneglect Modifies The Visuospatial After-Effects Of Vertical Prism Adaptation?

Objective:The prism adaptation (PA) with rightward shifting lenses is a promising rehabilitation technique for left hemispatial neglect. The PA has also been applied in healthy individuals to investigate cognitive mechanism(s) underlining such adaptation. Importantly, studies have suggested that PA may primarily impact the functions of the dorsal or the ventral attentional stream, and we have previously reported that PA to the upward and downward shifting lenses leads to a significant aftereffect in vertical line bisection task. However, this post-adaptation effect, similarly to that seen in the horizontal plane, might have been modified by the presence of the vertical pseudoneglect healthy participants often experience prior to PA. Thus, the aim of this study was to test this hypothesis.Participants and Methods:30 right-handed healthy adults (age M=22,4) performed a computerized line bisection (LB) in vertical and horizontal condition. The bisections were performed twice: before and after PA procedure. Participants took experimental procedure three times, each in at least 24 h of break, each time in one of three conditions of shifting lenses; down, up, control. Both LB tasks (vertical and horizontal) consisted of 24 lines, each centered on 23" touch screen. The participants were asked to find the middle of the line. Throughout the experiment, participants were comfortably seated with their head positioned on a chinrest. Participants were fitted with prismatic goggles that deviated their visual field by 10 degrees. For the adaptation we used the Peg-the-mole procedure consisting of 120 pointing movements.Results:To assess the effect of the vertical PA on landmark judgments we performed a repeated measures ANOVA with direction of PA (upward/downward), the condition of LB (vertical/ horizontal) and pre- vs post adaptation as a between-subjects factor. This analysis revealed a main effect of the direction of PA (p< 0.001) and a main effect of condition (p< 0.001). Overall, however, only adaptation in up-shifting lenses led to significant aftereffects (p<0.05). Further, when we excluded participants who did not exhibited horizontal pseudoneglect in preadaptation LB, the effect of PA in downshifting PA emerged in vertical LB (p<0.05). Further, this group also exhibited the aftereffect of PA in up-shifting lenses for the horizontal (p<0.01) and the vertical LB (p<0.05). Additionally, these participants exhibited a congruent tendency after upward and downward PA, and tended to allocate their attention more upward and rightward.Conclusions:The results of this study confirm that the vertical PA evokes a visuo-spatial bias. Moreover, the PA aftereffect seems to be modified by the presence of the pre-adaptation pseudoneglect. Whereas the mechanism inducing this bias is not fully known, it might be explained in light of the interhemispheric activation-inhibition balance. Both the upward and downward PA may primarily lead to activation of the posterior regions of the right hemisphere, and this activation may result with the upward and rightward bias in the LB task. However, future research with neuroimaging techniques is needed to test this hypothesis.

The interdependencies between the private and public sectors in open economies

Empirical evidence shows that countries with larger public sectors also have larger trade shares and a larger share of firms that export. These links between the public and the private sector are reconciled in an analytically tractable general equilibrium model allowing for a two-way causal relation between size (and the composition) of the public sector and openness and industry structure of the private sector. First, a larger public sector or a larger share of public expenditure used for public employment (alternative to transfers) results in a more open private sector (trade share and fraction of firms exporting), and it is also associated with more fat-tailedness of the firm size distribution, higher average productivity, lower average unit labour costs, and better wage competitiveness and terms of trade. These outcomes are driven by endogenous entry and selection of firms. Second, for optimal fiscal policies, international spillovers imply that non-cooperative policies have an upward bias in the overall size of the public sector, but a downward bias in transfers as a share of public expenditures. Trade liberalization and the degree of firm heterogeneity magnify these biases and thereby influence the size and structure of public expenditures.

A note on the prediction error of principal component regression in high dimensions

We analyze the prediction error of principal component regression (PCR) and prove high probability bounds for the corresponding squared risk conditional on the design. Our first main result shows that PCR performs comparably to the oracle method obtained by replacing empirical principal components by their population counterparts, provided that an effective rank condition holds. On the other hand, if the latter condition is violated, then empirical eigenvalues start to have a significant upward bias, resulting in a self-induced regularization of PCR. Our approach relies on the behavior of empirical eigenvalues, empirical eigenvectors and the excess risk of principal component analysis in high-dimensional regimes.

It Is Surprisingly Difficult to Measure Income Segregation

Recent studies have shown that U.S. Census– and American Community Survey (ACS)–based estimates of income segregation are subject to upward finite sampling bias (Logan et al. 2018; Logan et al. 2020; Reardon et al. 2018). We identify two additional sources of bias that are larger and opposite in sign to finite sampling bias: measurement error–induced attenuation bias and temporal pooling bias. The combination of these three sources of bias make it unclear how income segregation has trended. We formalize the three types of bias, providing a method to correct them simultaneously using public data from the decennial census and ACS from 1990 to 2015–2019. We use these methods to produce bias-corrected estimates of income segregation in the United States from 1990 to 2019. We find that (1) segregation is on the order of 50% greater than previously believed; (2) the increase from 2000 to the 2005–2009 period was much greater than indicated by previous estimates; and (3) segregation has declined since 2005–2009. Correcting these biases requires good estimates of the reliability of self-reported income and of the year-to-year volatility in neighborhood mean incomes.

Evaluation of MRI-based machine learning approaches for computer-aided diagnosis of dementia in a clinical data warehouse.

A variety of algorithms have been proposed for computer-aided diagnosis of dementia from anatomical brain MRI. These approaches achieve high accuracy when applied to research data sets but their performance on real-life clinical routine data has not been evaluated yet. The aim of this work was to study the performance of such approaches on clinical routine data, based on a hospital data warehouse, and to compare the results to those obtained on a research data set. The clinical data set was extracted from the hospital data warehouse of the Greater Paris area, which includes 39 different hospitals. The research set was composed of data from the Alzheimer's Disease Neuroimaging Initiative data set. In the clinical set, the population of interest was identified by exploiting the diagnostic codes from the 10th revision of the International Classification of Diseases that are assigned to each patient. We studied how the imbalance of the training sets, in terms of contrast agent injection and image quality, may bias the results. We demonstrated that computer-aided diagnosis performance was strongly biased upwards (over 17 percent points of balanced accuracy) by the confounders of image quality and contrast agent injection, a phenomenon known as the Clever Hans effect or shortcut learning. When these biases were removed, the performance was very poor. In any case, the performance was considerably lower than on the research data set. Our study highlights that there are still considerable challenges for translating dementia computer-aided diagnosis systems to clinical routine.

Low-degree solar rotational splitting from 45 yr of BiSON observations

ABSTRACT We present solar low-degree rotational splitting values based on a new analysis of Sun-as-a-star observations from the Birmingham Solar Oscillations Network, covering a 16 425-d period from 1976 December 31 to 2021 December 20 with a duty cycle of 57 per cent. The splitting values are estimated from the power spectrum using a Markov chain Monte Carlo sampling method, and we also present for comparison the results from an analysis of 100 realizations of synthetic data with the same resolution and gap structure. Comparison of the scatter in the results from the synthetic realizations with their estimated uncertainties suggests that for this data set the formal uncertainty estimates are about 30 per cent too small. An upward bias in the splittings at frequencies above 2200 μHz, where the components are not fully resolved, is seen in both the observed and synthetic data. When this bias is taken into account, our results are consistent with a frequency-independent synodic rotational splitting value of 400 nHz.

Altered Allocation of Vertical Attention in Individuals With Autism Spectrum Disorder.

Typical adults most frequently orient their attention to other people's eyes, whereas individuals with autism spectrum disorder (ASD) orient their attention to other people's mouths. Typical adults also reveal visuospatial biases on tasks such as vertical and horizontal line bisections. Therefore, the difference in face viewing might be related to a more general group difference in the allocation of vertical attention. To use vertical line bisection and quadrisection tasks to evaluate whether individuals with ASD have a more downward-oriented vertical attentional bias than do typical individuals. We recruited 20 individuals with ASD and 20 control participants matched for age (6-23 years), IQ, and sex. We asked the individuals to bisect and quadrisect lines on the top and bottom when the vertical lines were placed at the intersection of their right, left, and center egocentric sagittal planes and their coronal plane. The distances from the true midpoint and quadripoint were measured, and between-group performances were compared. No significant difference was found between the ASD and control groups for vertical line bisections or lower line quadrisections. However, when the ASD group was compared with the control group for higher line quadrisections, the ASD group exhibited a greater upward deviation. There is no downward vertical attentional spatial bias associated with ASD that could help to explain these individuals' attentional bias toward the mouth. However, additional studies are required to learn if this atypical upward vertical attentional bias might account for some of the symptoms and signs associated with ASD.

Accounting Bias and Debt Contracting

This study investigates the effects of accounting bias on the efficiency of a debt-financed investment, which is subject to an interim liquidation/continuation decision based on the accounting report. We decompose the overall effect of accounting bias into a mean effect and a variance effect and transform binary state and report spaces into continuous ones. We derive two main results. (1) The highest investment efficiency is induced by a downward bias for gloomy investment prospects and an upward bias for rosy investment prospects. (2) The optimal covenant tightness is U-shaped and the optimal interest rate is hump-shaped in the degree of bias. In particular, neutral (unbiased) accounting neither minimizes the variance of the report nor maximizes investment efficiency.

Can Measurement Error Explain Slow Productivity Growth in Construction?

Of all major industries, construction is the only one to have registered negative average productivity growth since 1987. One might suspect measurement error to have biased growth downward since the deflators for this sector, which are used to translate nominal construction spending into the real quantity of structures, have risen much faster than those for other sectors. We find evidence of an upward bias in these deflators related to unobserved improvements in structure quality, but the magnitude is not large enough to alter the view that construction-sector productivity growth has been weak. We also find only small contributions from other potential sources of measurement error. We conclude that productivity growth may well have been quite low in construction, even if it has not been as low as implied by official statistics.

The effect of FDI on the host countries’ employment: A meta-regression analysis

This study performed a meta-regression analysis (MRA) to reexamine the effect of foreign direct investment (FDI) on the host countries’ employment. We detected a publication bias and heterogeneity between studies by employing 61 publications with 477 estimates as the dataset. Studies that do not control for endogeneity suffer an upward publication bias. In contrast, we found a downward publication bias in the studies that control endogeneity. After correcting that bias, we found a small positive effect of FDI on the host countries’ employment as the genuine effect. By using the Bayesian Model Averaging (BMA) analysis, we found six moderator variables that could explain heterogeneity. These moderator variables are related to the FDI and employment measurement type, data characteristics, FDIreceiving countries, and estimation methods.

Using Age-Specific Values for Pediatric HRQoL in Cost-Effectiveness Analysis: Is There a Problem to Be Solved? If So, How?

Value sets for the EQ-5D-Y-3L published to date appear to have distinctive characteristics compared with value sets for corresponding adult instruments: in many cases, the value for the worst health state is higher and there are fewer values < 0. The aim of this paper is to consider how and why values for child and adult health differ; and what the implications of that are for the use of EQ-5D-Y-3L values in economic evaluations to inform healthcare resource allocation decisions. We posit four potential explanations for the differences in values: (a) The wording of severity labels may mean the worst problems on the EQ-5D-Y-3L are descriptively less severe than those on the EQ-5D-5L; (b) Adults may genuinely consider that children are less badly affected than adults by descriptively similar health issues. That is, for any given health problem, adult respondents in valuation studies consider children's overall health-related quality of life (HRQoL) on average to be higher than that for adults; (c) Values are being sought by eliciting adults' stated preferences for HRQoL in another person, rather than in themselves (regardless of whether the 'other person' concerned is a child); and (d) The need to elicit preferences for child HRQoL that are anchored at dead = 0 invokes special considerations regarding children's survival. Existing evidence does not rule out the possibility that (c) and (d) exert an upward bias in values. We consider the implications of that for the interpretation and use of values for pediatric HRQoL. Alternative methods for valuing children's HRQoL in a manner that is not 'age specific' are possible and may help to avoid issues of non-comparability. Use of these methods would place the onus on health technology assessment bodies to reflect any special considerations regarding child quality-adjusted life-year gains.

Wheat price volatility regimes over 140 years: An analysis of daily price ranges

We analyze Chicago based daily wheat price volatility over more than 140 years using a novel data set of daily high and low futures prices starting in 1877. We identify five long-run regimes and find that volatility shifts between regimes are statistically more pronounced than fluctuations within regimes, even when conditioning on economic states. Historical volatility estimates derived from average commodity price data, a common practice in empirical studies, exhibit a regime-dependent upward bias between 0% and 22%. The magnitude of the bias and the importance of regimes potentially explain contradictory findings on volatility patterns in earlier studies.

Influence of the spatial grid type on the result of calculating the neutron fields in the nuclear power plant shielding

The paper considers the influence of the spatial grid type on the result of solving the equation of neutron transport in the nuclear power plant (NPP) shielding. Neutron fields were calculated in a realistic model of a liquid metal cooled fast neutron tank reactor with an integral equipment layout. Structured cubic and unstructured hexahedral grids (pmsnsys and FRIGATE codes) and unstructured tetrahedral and prismatic grids (RADUGA T code) are used. Limiting values of the group fluxes averaged over the material zones for refined grids have been obtained. It has been shown that the calculation results depend on the type of approximation for the curvilinear inner boundaries between the material zones rather than on the grid cell type (cube, hexahedron, tetrahedron, prism). Using “toothed” approximations for curvilinear boundaries leads to an increase in the area of the boundaries, as well as to the neutron flux refraction condition arising on them. These effects lead to an upward bias in the transport equation solution, and for all energy groups. Conclusion. When solving an equation of neutron transport in the NPP shielding by a grid technique, it is necessary to use grids other than leading to “toothed” approximations of the inner boundaries. Tetrahedral or prismatic grids, or grids of arbitrary hexahedrons can be recommended, as well as composite grids in which cubic cells are located inside the material zone, and hexahedron cells are located near the zone boundary.

Exploring Upward and Downward Provider Biases in Family Planning: The Case of Parity.

Provider bias has become an important topic of family planning research over the past several decades. Much existing research on provider bias has focused on the ways providers restrict access to contraception. Here, we propose a distinction between the classical "downward" provider bias that discourages contraceptive use and a new conception of "upward" provider bias that occurs when providers pressure or encourage clients to adopt contraception. Using cross-sectional data from reproductive-aged women in Burkina Faso, we describe lifetime prevalence of experiencing provider encouragement to use contraception due to provider perceptions of high parity (a type of upward provider bias) and provider discouragement from using contraception due to provider perceptions of low parity (a type of downward provider bias). We also examine associations between sociodemographic characteristics and experiences of provider encouragement to use contraception due to perceptions of high parity. Sixteen percent of participants reported that a provider had encouraged them to use contraception due to provider perceptions of high parity, and 1% of participants reported that a provider had discouraged them from using contraception because of provider perceptions of low parity. Being married, being from the rural site, having higher parity, and having attended the 45th-day postpartum check-up were associated with increased odds of being encouraged to use contraception due to provider perceptions of high parity. We find that experiences of upward provider bias linked to provider perceptions of high parity were considerably more common in this setting than downward provider bias linked to perceptions of low parity. Research into the mechanisms through which upward provider bias operates and how it may be mitigated is imperative to promote contraceptive autonomy.