Causal identification with subjective outcomes

Survey questions often elicit responses on ordered scales for which the definitions of the categories are subjective, possibly varying by individual. This paper clarifies what is learned when these subjective reports are used as an outcome in regression-based causal inference. When a continuous treatment variable is statistically independent of both i) potential outcomes; and ii) heterogeneity in reporting styles, a nonparametric regression of integer category numbers on that variable uncovers a positively-weighted linear combination of causal responses among individuals who are on the margin between adjacent response categories. Though the weights do not integrate to one, the ratio of local regression derivatives with respect to two such explanatory variables identifies the relative magnitudes of convex averages of their effects. When results are extended to discrete treatment variables, different weighting schemes apply to different regressors, making comparisons of magnitude less informative. I obtain a partial identification result for comparing the effects of a discrete treatment variable to those of another treatment variable when there are many categories and individual reporting functions are linear. I also provide results for identification using instrumental variables

A Vector Monotonicity Assumption for Multiple Instruments

When a researcher wishes to use multiple instrumental variables for a single binary treatment, the familiar LATE monotonicity assumption can become restrictive: it requires that all units share a common direction of response even when different instruments are shifted in opposing directions. What I call vector monotonicity, by contrast, simply restricts treatment status to be monotonic in each instrument separately. This is a natural assumption in many contexts, capturing the intuitive notion of "no defiers" for each instrument. I show that in a setting with a binary treatment and multiple discrete instruments, a class of causal parameters is point identified under vector monotonicity, including the average treatment effect among units that are responsive to any particular subset of the instruments. I propose a simple "2SLS-like" estimator for the family of identified treatment effect parameters. An empirical application revisits the labor market returns to college education.Comment: 56 pages, 6 figure

Treatment Effects in Bunching Designs: The Impact of Mandatory Overtime Pay on Hours

The 1938 Fair Labor Standards Act mandates overtime premium pay for most U.S. workers, but it has proven difficult to assess the policy's impact on the labor market because the rule applies nationally and has varied little over time. I use the extent to which firms bunch workers at the overtime threshold of 40 hours in a week to estimate the rule's effect on hours, drawing on data from individual workers' weekly paychecks. To do so I generalize a popular identification strategy that exploits bunching at kink points in a decision-maker's choice set. Making only nonparametric assumptions about preferences and heterogeneity, I show that the average causal response among bunchers to the policy switch at the kink is partially identified. The bounds indicate a relatively small elasticity of demand for weekly hours, suggesting that the overtime mandate has a discernible but limited impact on hours and employment

Changing Principals\u27 Leadership through Feedback and Coaching

Researchers Leonard Bickman, Ellen Goldring, Peter Goff, and J. Edward Guthrie conducted a randomized experiment of principals in a large urban school district to explore if coaching, when combined with feedback from teachers, changes principals’ leadership practices. This brief summarizes the research findings regarding the impact of the feedback and coaching intervention on principals’ leadership behaviors

Particle motion during the compaction of granular matter

We track particle motions in a granular material subjected to compaction using a laser scattering based imaging method where compaction is achieved through thermal cycling. Particle displacements in this jammed fluid correlate strongly with rearrangments of the Voronoi cells defining the local spatial partitioning about the particles, similar to previous observations of Rahman on cooled liquids. Our observations provide further evidence of commonalities between particle dynamics in granular matter close to jamming and supercooled liquids.Comment: 4 pages, 6 Figures, to be submitted to PR

Classical simulation of measurement-based quantum computation on higher-genus surface-code states

We consider the efficiency of classically simulating measurement-based quantum computation on surface-code states. We devise a method for calculating the elements of the probability distribution for the classical output of the quantum computation. The operational cost of this method is polynomial in the size of the surface-code state, but in the worst case scales as $2^{2g}$ in the genus $g$ of the surface embedding the code. However, there are states in the code space for which the simulation becomes efficient. In general, the simulation cost is exponential in the entanglement contained in a certain effective state, capturing the encoded state, the encoding and the local post-measurement states. The same efficiencies hold, with additional assumptions on the temporal order of measurements and on the tessellations of the code surfaces, for the harder task of sampling from the distribution of the computational output.Comment: 21 pages, 13 figure

Clinical Outcomes in Patients with Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Bloodstream Infection

The prevalence of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) infections varies in the literature, a problem complicated by the lack of routine screening procedures; however, limited data suggest that hVISA has been associated with persistent bloodstream infections (BSI) and vancomycin failure, yet these studies have been confounded by design issues. We conducted this study to compare the characteristics of patients with BSI caused by hVISA with those with vancomycin-susceptible Staphylococcus aureus (VSSA) treated with vancomycin. This retrospective, multicenter matched (1:1) cohort study compared the clinical characteristics and outcomes of hVISA and VSSA. Patients with hVISA methicillin-resistant Staphylococcus aureus (MRSA) BSI from 2004 to 2012 were matched to VSSA-MRSA BSI patients. The primary outcome was failure of vancomycin treatment, defined as a composite of persistent bacteremia (≥7 days), persistent signs and symptoms, change of MRSA antibiotic, recurrent BSI, or MRSA-related mortality. We identified 122 matched cases. The overall vancomycin failure rate was 57% (82% hVISA versus 33% VSSA; P \u3c 0.001). The individual components of failure in hVISA versus VSSA were persistent bacteremia, 59% versus 21% (P \u3c 0.001); change in MRSA therapy, 54% versus 25% (P = 0.001); MRSA-related mortality, 21% versus 10% (P = 0.081); and recurrence of BSI, 26% versus 2% (P \u3c 0.001). Using logistic regression analysis and adjusting for covariates, hVISA (adjusted odds ratio [aOR], 11.1; 95% confidence interval [CI], 4.3 to 28.7) and intensive care unit (ICU) admission (aOR, 4.5; 95% CI, 1.8 to 11.6) were still independently associated with vancomycin failure. Relative to VSSA BSI, patients with hVISA were more likely to experience failure of vancomycin treatment, including persistent bacteremia and recurrence. Our results indicate that hVISA was responsible for considerable morbidity

Reaction Time Effects of Related and Unrelated Visual and Auditory Semantic Distraction on Picture Identification in Younger and Older Adults

Models for understanding effects of distraction on linguistic processing are few. We measured semantically related and unrelated visual and auditory ambient distraction on picture identification in non-neurologically damaged younger and older adults. Comparisons were made across conditions of quiet, white noise, visual, and auditory distraction for categories of sports and vegetables. The effect of semantic relatedness varied according to modality of distraction. Visual distraction of semantically related targets hindered performance more than unrelated visual distraction. Both groups performed slower during distraction compared to quiet. Older adults demonstrated significantly longer reaction times during conditions of either auditory or visual distraction