3-sigma Limits Research Articles

Comparison of risk-adjusted cumulative quality control charts compared with standardized mortality ratios in critical care.

The optimal method for monitoring intensive care unit (ICU) performance is unknown. We sought to compare process control charts using standardized mortality ratio (SMR), p-charts, and cumulative sum (CUSUM) charts for detecting increases in risk-adjusted mortality within ICUs. Using data from 17 medical-surgical ICUs that included 29,592 patients in Ontario, Canada, we created risk-adjusted p-charts and SMRs on monthly intervals and CUSUM charts. We defined positive signals as any data point that was above the 3-sigma limit (approximating a 99% confidence interval [CI]) on a p-chart, any data point whose 95% CI did not include 1 for the SMR charts, and when a data point exceeded control limits for an odds ratio of 1.5 for CUSUM charts. We simulated increases in mortality of 10%, 30%, and 50% for each ICU to determine the sensitivity of each method. We calculated sensitivity as the number of positive signals divided by the number of ICUs (equal to number of simulated events). Cumulative sum charts generated 31 signals in 12 different ICUs, while p-charts and SMR agreed in 10 and 6 of these signals, respectively, followed by 21 signals from p-charts across 14 ICUs (agreement in 10 of these signals for both CUSUM and SMR) and 15 signals from SMR charts across eight ICUs (agreement from p-charts and CUSUM in 10 and six signals, respectively). The p-chart had a sensitivity of 88% (95% CI, 73 to 104) for a 50% simulated increase in ICU mortality followed by CUSUM at 71% (95% CI, 49 to 102) and SMR at 59% (95% CI, 35 to 82). Performance with lower simulated increases was poor for all three methods. P-charts created with risk-adjusted mortality at monthly intervals are potentially useful tools for monitoring ICU performance. Future studies should consider usability testing with ICU leaders and application of these methods to additional clinical domains.

Improved oral anticancer medication (OAM) adherence/toxicity assessment documentation.

409 Background: Based on national OAM guidelines and to improve patient safety, most OAM programs monitor toxicity/adherence within 10-14 days following OAM initiation. At our institution, only 50% of toxicity/adherence documentation tasks were completed by day 10 of cycle 1 after initiating OAM. We aimed to increase toxicity/adherence documentation tasks to at least 75% by day 10 of cycle 1 following a newly prescribed OAM in collaboration with Hematology/Oncology Pharmacy Association/American Society of Clinical Oncology 2022 quality training program (QTP). Methods: We engaged a multidisciplinary team to gather/interpret data, create process map, and identify barriers. Outcome measure was documentation of toxicity/adherence by day 10 of cycle 1. Included all cancer patients initiating OAM treatment plan. Excluded those on intravenous/oral regimens and gynecology/oncology patients. Process measure was percentage of 9 crucial tasks identified as necessary to appropriately document toxicity/adherence. Balance measures included provider visits, emergency department visits, telephone/electronic medical record OAM-related messages, and nursing satisfaction. A cause-and-effect diagram, pareto chart and prioritization matrix were used to narrow focus of improvement changes. Two plan-do-study-act (PDSA) cycles were conducted from January 2023-June 2023. All data were analyzed using Statistical Process Control Charts with 3-sigma control limits. Results: Original high-impact, easy-to-implement intervention (re-training staff) delayed due to institutional-directed intervention (education documentation retraining due to The Joint Commission survey). Education documentation retraining did not significantly improve toxicity/adherence task completion rate (50% to 53%) by improved provider and emergency department visits (16.7% and 12.5% to 0%) (see Table 1). Nursing turnover, lack of formal OAM process training and institutional buy-in for OAM program/training likely contributed to results. Re-training supported with institutional buy-in completed. PDSA cycle 2 data collection is ongoing; preliminary results show no change in task completion rate. Conclusions: Education documentation and retraining alone is insufficient to improve OAM toxicity/adherence documentation rates. Other interventions are needed to attain our goal.[Table: see text]

Clinical pharmacist prescription review and modification for oral antineoplastic medications at an academic medical center.

64 Background: Collaboration between oncology providers and pharmacy teams has improved the safety of oral antineoplastic (OA) prescribing, but opportunities remain for improvements in care delivery. To this end, starting in March 1, 2021, the Dana Farber Cancer Institute Specialty Pharmacy implemented a new workflow - clinical verification of new specialty prescriptions by dedicated OA clinical pharmacists (OAPs) prior to prescription processing. To reduce the impact of initial prescription errors on efficiency and safety, one component of clinical verification was to expand the purview of OAPs to make certain modifications to prescriptions that could be automatically processed without requiring prescriber re-signing. Automatically processed prescription modifications include corrections to quantity or days supply, indication of cycle length or days on/off therapy, and clarification of directions. Here we report on the impact of this portion of the clinical verification program. Methods: OAP prescription modification (OAP-PM) was introduced on November 1, 2022. To assess the impact on efficiency, we conducted a pre-post analysis of the proportion of prescription modifications taking > 60 minutes to complete for 6 months before and after OAP-PM introduction. Using prescription-level data, we analyzed co-variates including pre-/post-OAP-PM, patient age (continuous), site (academic vs. network), communication with someone other than the primary prescriber (y/n), and medication category (anti-neoplastic vs. supportive). We used control charts to explore the contribution of specific medications and sites that might share best practices or be the focus of subsequent, more focused improvement projects. Results: From May 1, 2022 to May 1, 2023, 458 prescription modifications were completed, 180 pre- and 278 post-OAP-PM. The proportion of prescriptions requiring > 60 minutes to complete decreased from 29.4% to 19.8% (p = 0.0184). In multivariable regression, the significant predictors of prescription taking > 60 minutes to complete were pre-OAP-PM (LR 4.9, p = 0.027); network (LR 20.8, p < 0.0001); and communication with someone other than the primary provider (LR 18.6, p < 0.0010). Control charts demonstrated all sites were within 3-sigma limits pre- and post-OAP-PM, but with wide limits at many sites. Individual medications could not be meaningfully analyzed due to the small sample sizes. Conclusions: OAP-PM successfully reduced the proportion of OA prescriptions taking more than an hour to modify. This may be a useful workflow change for other specialty pharmacies to adopt to improve the efficiency of OA care. Additional work is needed to understand whether site-, provider- or medication-specific changes can improve upon this model.

Leveraging Real-world Data to Increase Procedure Room Capacity: A Multidisciplinary Quality Improvement Project.

In the current healthcare climate, the financial strain created by COVID-19, limited resources, and case backlogs highlight the need to optimize operating and procedure room efficiency and maximize capacity. At Seattle Children's, a clinical multidisciplinary team developed and implemented a data-driven protocol to improve efficiency in a high-volume gastrointestinal (GI) suite. Key process measures, including all case on-time starts and postanesthesia care unit length of stay, were extracted from the electronic medical record and presented as Statistical Process Control (SPC) charts. Clinicians' performance was stratified by rational subgrouping to better understand variation in the system. We defined an expert clinician as one who performs beyond 3-sigma limits on funnel plot analyses. We developed clinical protocols based on expert clinician clinical practices. We gave clinicians dynamic, daily feedback on this family of measures through continuously updated SPC charts. This real-world data drove system and individual-level plan-do-check-act improvement cycles. Despite significant external challenges over 2 years, procedure volume increased by approximately 25%, on-time starts improved by 36%, turnover time decreased by 34%, and postanesthesia care unit length of stay decreased by 15%. GI laboratory revenue increased by approximately 25% (independent of increased charges per procedure), representing the potential for a $2 million increase in annual revenue. A multidisciplinary clinical team improved efficiency metrics in a busy pediatric GI suite. Access to real-world data through continuously updated SPC charts enabled plan-do-check-act cycles that led to measurable improvement. This data access also served to sustain team motivation and engagement.

Effect of Parameter Estimation on the Performance of Shewhart <img src=image/13425522_01.gif>-joint Chart Looked at in Terms of the Run Length Distribution

Using spread-charts to monitor process variation and thereafter using the <img src=image/13425522_02.gif>-chart to monitor the process mean after is a common practice. To apply these charts independently using estimated 3-sigma limits is common. Recently, some authors considered the application of <img src=image/13425522_02.gif> and R-charts together as a charting scheme, <img src=image/13425522_01.gif>-chart when the standards are known, Case KK, only the mean standard is known, Case KU and both standards unknown, Case UU. The average run length (ARL) performance criterion was used. However, because of the skewed nature of the run length (RL) distribution, many authors have frowned at the use of ARL as a sole performance measure and encouraged the percentiles of the RL distribution instead. Therefore, the cdfs of the RLs of the chart under the cases mentioned will be derived in this work, and the percentiles are used to look at the chart for Case KU and the yet to be considered case of the chart, Case UK where only the process variance is known is included for comparison. These are the contribution to the existing literature. <img src=image/13425522_01.gif>-chart performed better in Case KU than in Case UK and the unconditional in-control median run length described the behavior of the chart better than the in-control ARL.

Physical Properties Analysis and Quality Assessment of Gypsum-Kalsiboard Marketed in Ambon City

The objectives of this research were to analyse the physical properties and quality assessment of Gypsum Kalsiboard in the Ambon city market so that the physical properties of the boards and their quality are analysed and controlled. The material used was composite board in the form of gypsum-kalsiboard panels with length of 244.0 cm, width of 122.0 cm and thickness of 3.5 mm. This experimental model used Completely Randomized Design (CRD) and assessment the quality by control chart evaluated using 3-sigma control limits through the Upper Control Limit (UCL) and lower control limit (LCL). The result showed that the average of overall density was about of 1.41 g/cm3, moisture content of 9.12%, water absorption of 25.21% and thickness swelling about of 1.91% which meets the standard limits required by SNI No. 03-6434-2000. Although by quality assessment there were several points that are above the upper control limit (UCL) and below the lower control limit (LCL), the physical properties values of this board were still within the tolerance limits because the condition of the board does not show significant changes such as those related to water absorption and thickness swelling, indicating that the board was quite stable and high dimensional stability after 24 hours of immersion.

Minimizing the risk of Clostridium difficile infection as an early complication of autologous stem cell transplantation.

219 Background: Clostridium difficile infection (CDI) is one of the most important affecting patients immunocompromised by autologous stem cell transplantation (ASCT), and can be associated with increased morbidity and length of stay. One precipitating factor for index CDI cases in the ASCT population is heavy antibiotic exposure, which often includes prophylaxis. A retrospective review identified 11 cases of CDI (17%) in the 30-day period following ASCT performed at the University of Virginia Medical Center (UVAMC) between about June 2016 and July 2017. Various institutional and multicenter studies have reported incidence rates in this population ranging from less than 5% to more than 10%. Methods: To decrease CDI rate, a multidisciplinary team comprised of oncology and infectious diseases physicians, pharmacists, and nurses was formed. The group used quality improvement principles to identify and target areas of greatest significance. A first PDSA cycle was conducted between approximately July 2017 and June 2018, during which time administration of standard-of-care ciprofloxacin prophylaxis between T+0 and count recovery was suspended. A second PDSA cycle was executed between approximately May 2018 and July 2019, incorporating UV light equipment into existing post-discharge cleaning practices. Data were analyzed using process control charts with 3-sigma limits for ASCT length-of-stay (LOS) and 30-day post-transplant CDI incidence. Results: Suspension of prophylactic antibiotics did not have a significant effect on CDI incidence in our first PDSA cycle. In our second improvement cycle, most of which elapsed after prophylactic ciprofloxacin had been re-implemented, CDI incidence was almost halved, from 17 to 9%. A numerical decreased in LOS was observed in each subsequent PDSA cycle. Conclusions: Our multidisciplinary team applied quality improvement methods to drive a clinically significant reduction in the 30-day CDI incidence after ASCT at UVAMC. This outcome should be associated with an improved patient experience. Future PDSA cycles are scheduled and may include other cancer patients, beyond those receiving stem cell transplantation.[Table: see text]

Monitoring Hospital Performance with Statistical Process Control After Total Hip and Knee Arthroplasty: A Study to Determine How Much Earlier Worsening Performance Can Be Detected.

Given the low early revision rate after total hip arthroplasty (THA) and total knee arthroplasty (TKA), hospital performance is typically compared using 3 years of data. The purpose of this study was to assess how much earlier worsening hospital performance in 1-year revision rates after THA and TKA can be detected. All 86,468 THA and 73,077 TKA procedures performed from 2014 to 2016 and recorded in the Dutch Arthroplasty Register were included. Negative outlier hospitals were identified by significantly higher O/E (observed divided by expected) 1-year revision rates in a funnel plot. Monthly Shewhart p-charts (with 2 and 3-sigma control limits) and cumulative sum (CUSUM) charts (with 3.5 and 5 control limits) were constructed to detect a doubling of revisions (odds ratio of 2), generating a signal when the control limit was reached. The median number of months until generation of a first signal for negative outliers and the number of false signals for non-negative outliers were calculated. Sensitivity, specificity, and accuracy were calculated for all charts and control limit settings using outlier status in the funnel plot as the gold standard. The funnel plot showed that 13 of 97 hospitals had significantly higher O/E 1-year revision rates and were negative outliers for THA and 7 of 98 hospitals had significantly higher O/E 1-year revision rates and were negative outliers for TKA. The Shewhart p-chart with the 3-sigma control limit generated 68 signals (34 false-positive) for THA and 85 signals (63 false-positive) for TKA. The sensitivity for THA and TKA was 92% and 100%, respectively; the specificity was 69% and 51%, respectively; and the accuracy was 72% and 54%, respectively. The CUSUM chart with a 5 control limit generated 18 signals (1 false-positive) for THA and 7 (1 false-positive) for TKA. The sensitivity was 85% and 71% for THA and TKA, respectively; the specificity was 99% for both; and the accuracy was 97% for both. The Shewhart p-chart with a 3-sigma control limit generated the first signal for negative outliers after a median of 10 months (interquartile range [IQR] = 2 to 18) for THA and 13 months (IQR = 5 to 18) for TKA. The CUSUM chart with a 5 control limit generated the first signal after a median of 18 months (IQR = 7 to 22) for THA and 21 months (IQR = 9 to 25) for TKA. Monthly monitoring using CUSUM charts with a 5 control limit enables earlier detection of worsening 1-year revision rates with accuracy so that initiatives to improve care can start earlier.

Neutrino phenomenology and dark matter in an A_4 flavour extended B-L model

We present an {mathrm{A}}_4 flavor extended {mathrm{B-L}} model for realization of eV scale sterile neutrinos, motivated by the recent experimental hints from both particle physics and cosmology. The framework considered here is a gauged {mathrm{B-L}} extension of standard model without the introduction of right-handed neutrinos, where the gauge triangle anomalies are canceled with the inclusion of three exotic neutral fermions N_{i} (i=1,2,3) with {mathrm{B-L}} charges -,4,-,4 and 5. The usual Dirac Yukawa couplings between the SM neutrinos and the exotic fermions are absent and thus, the model allows natural realization of eV scale sterile-like neutrino and its mixing with standard model neutrinos by invoking {mathrm{A}}_4 flavor symmetry. We demonstrate how the exact tri-bimaximal mixing pattern is perturbed due to active-sterile mixing by analyzing 1+3 case in detail. We also show the implication of eV scale sterile-like neutrino on various observables in neutrino oscillation experiments and the effective mass in neutrinoless double beta decay. Another interesting feature of the model is that one of three exotic fermions is required to explain eV scale phenomena, while other two fermions form stable dark matter candidates and their total relic density satisfy the observed 3sigma limit of Planck data. We constrain the gauge parameters associated with U(1) gauge extension, using relic density and collider bounds.

Asteroid mass estimation with the robust adaptive Metropolis algorithm

Context. The bulk density of an asteroid informs us about its interior structure and composition. To constrain the bulk density, one needs an estimated mass of the asteroid. The mass is estimated by analyzing an asteroid’s gravitational interaction with another object, such as another asteroid during a close encounter. An estimate for the mass has typically been obtained with linearized least-squares methods, despite the fact that this family of methods is not able to properly describe non-Gaussian parameter distributions. In addition, the uncertainties reported for asteroid masses in the literature are sometimes inconsistent with each other and are suspected to be unrealistically low. Aims. We aim to present a Markov-chain Monte Carlo (MCMC) algorithm for the asteroid mass estimation problem based on asteroid-asteroid close encounters. We verify that our algorithm works correctly by applying it to synthetic data sets. We use astrometry available through the Minor Planet Center to estimate masses for a select few example cases and compare our results with results reported in the literature. Methods. Our mass-estimation method is based on the robust adaptive Metropolis algorithm that has been implemented into the OpenOrb asteroid orbit computation software. Our method has the built-in capability to analyze multiple perturbing asteroids and test asteroids simultaneously. Results. We find that our mass estimates for the synthetic data sets are fully consistent with the ground truth. The nominal masses for real example cases typically agree with the literature but tend to have greater uncertainties than what is reported in recent literature. Possible reasons for this include different astrometric data sets and weights, different test asteroids, different force models or different algorithms. For (16) Psyche, the target of NASA’s Psyche mission, our maximum likelihood mass is approximately 55% of what is reported in the literature. Such a low mass would imply that the bulk density is significantly lower than previously expected and thus disagrees with the theory of (16) Psyche being the metallic core of a protoplanet. We do, however, note that masses reported in recent literature remain within our 3-sigma limits. Results. The new MCMC mass-estimation algorithm performs as expected, but a rigorous comparison with results from a least-squares algorithm with the exact same data set remains to be done. The matters of uncertainties in comparison with other algorithms and correlations of observations also warrant further investigation.

Guidelines for automating Phase I of control charts by considering effects on Phase-II performance of individuals control chart

With the advances in measurement technologies, today products and processes may have hundreds of variables that can be monitored. As the number of variables to be monitored in a process increases, a cumbersome task is the design of control charts, especially when one needs to estimate unknown process parameters. In Phase-I control chart implementations, a set of samples that are ideally from an in-control process is formed by iteratively eliminating/retaining potentially out-of-control samples and this is then used in parameter estimation. Nevertheless, sampling variability and samples from an out-of-control process that are not eliminated from a Phase-I data set may have effects on the online process monitoring (Phase II) performance of a control chart due to the control chart design with estimation errors. To provide Phase-I control chart design guidelines, here we investigate in detail the iterative use of the individuals control chart (I-control chart) in Phase I for identifying potentially out-of-control process observations when the initial Phase-I data set consists of contaminated observations, which is then followed by another Phase-II I-control chart designed with the parameter estimates obtained in Phase I. Using the sample size and the width of I-chart’s control limits as design factors in Phase I, process parameters are estimated, and these are used to design an I-chart with 3-sigma control limits for Phase II. In Phase II, expected value (AARL) and standard deviation (SDARL) of the average run lengths are evaluated. Six standard deviation estimators and three different contamination levels are considered. Guidelines for selecting the control limit width, sample size, and standard deviation estimator for the Phase I implementations are provided to yield desirable Phase II AARL performance with a small SDARL. Our contribution is neither in the theory of control charts nor in the individual techniques. Results of this study would be especially useful in automating control chart design processes where there are many control charts to be designed by well-trained operators in statistical process control. With transformations to Industry 4.0, which is a trend for automation and data exchange in manufacturing, utility of procedures for control chart design automation is expected to increase.

Tracking quality: can embryology key performance indicators be used to identify clinically relevant shifts in pregnancy rate?

Can embryology key performance indicators (KPIs) detect shifts in laboratory performance that precede changes in clinical outcomes? Day 5 usable blastocyst rate (D5BUR) is an important embryology KPI that complements total usable blastocyst rate (TBUR) in its ability to rapidly identify adverse embryology outcomes, prior to changes in clinical outcomes. The hypothesis that monitoring performance of an IVF laboratory using statistical process controls (SPCs) can act as an early warning signal of shifts in laboratory conditions is a hypothesis that requires validation. The Vienna consensus report recently defined KPIs for monitoring fresh IVF and ICSI cycles, but the effectiveness of using these KPIs for detecting clinically relevant shifts following changes in laboratory processes is unknown. A retrospective, multicentre, analysis of KPIs for 1971 fresh IVF and ICSI cycles during three consecutive 5-month periods (P1, P2 and P3) during which the culture medium was changed in the middle period. ICSI fertilisation rate, IVF fertilisation rate, D5BUR, TBUR and clinical pregnancy rate (CPR) were tracked monthly and analysed for SPC using Shewhart control charts. Out-of-control KPIs were identified by warning (2-sigma) and control (3-sigma) limits. The effect of the laboratory culture medium change on embryology KPIs and cumulative CPR was investigated using a one-way ANOVA or Pearson Chi-squared test and logistic regression. D5BUR decreased from 32 to 25% after the culture medium was changed, and the decrease was detected within 1 week after the change (P < 0.0001). D5BUR subsequently increased after a change back to the original medium. A decrease in CPR (51-36%) after the medium change was also observed but was not detected until 3 months after the shift in D5BUR (P = 0.0005). Overall, the change in culture medium independently influenced D5BUR, CPR and cumulative CPR. Importantly, TBUR (41%) was not affected by the change in culture medium, remaining within control limits for all three culture periods, indicating that the overall blastocyst rate alone may not sufficiently monitor embryology laboratory performance. The statistical KPI monitoring system demonstrated by the current study may be less effective at identifying KPI shifts in smaller clinics with lower cycle volumes. Live-birth rate per cycle started was not included as a clinical KPI. This study demonstrates that statistical KPI monitoring systems have the potential to provide systematic, early detection of adverse outcomes in ART laboratories after planned or unexpected shifts in conditions. No external funds were used for the study. The authors have no conflicts of interest. Not applicable.

Day 5 useable blastocyst rate is an early indicator of clinically significant shifts in the embryo culture system

The ability to track performance of an IVF laboratory using statistical process controls has not been validated and remains an important goal for an early warning signal of shifts in laboratory conditions. The Vienna consensus report recently defined Key Performance Indicators (KPIs) for monitoring fresh IVF and ICSI cycles, but the effectiveness of these KPIs for detecting clinically relevant shifts following changes in laboratory processes is unknown1. The aim of this study was to assess whether embryology KPIs detect shifts in laboratory performance that result in changes in clinical outcomes. Retrospective, multicentre, analysis of KPIs for fresh IVF and ICSI cycles. Three consecutive 5-month periods of embryo culture media were investigated 1) embryo culture in Continuous Single Culture Complete (CSCM-C) (Irvine Scientific) 2) embryo culture in G-TL (Vitrolife) 3) embryo culture returned to CSCM-C (Irvine Scientific). Six primary embryology KPIs were tracked for 1523 cycles from June 2016 to August 2017; ICSI fertilization rate, IVF fertilization rate, useable day 5 blastocyst rate, overall useable blastocyst rate, clinical pregnancy rate and cumulative clinical pregnancy rate. Meaningful KPI shifts were identified by upper and lower warning (2-sigma) and control (3-sigma) limits. KPI shifts were analyzed by ANOVA and multivariate regression. During the 15 months analyzed, the novel KPI, useable day 5 blastocyst rate, fell below the 3-sigma lower control limit for 5 months. The decrease in useable day 5 blastocyst rate, from 43% to 32%, occurred following a change from CSCM-C (Irvine Scientific) to G-TL (Vitrolife) and was detected one week after the change (p < 0.0001). Useable day 5 blastocyst rate subsequently recovered after a change back to CSCM-C (p < 0.0001). A decrease in clinical pregnancy rate (54% to 41%) was also observed, but this was not detected until 3 months after the useable day 5 blastocyst rate shift (p = 0.01). Although culture media type independently effected useable day 5 blastocyst rate and clinical pregnancy rate, the cumulative clinical pregnancy rate was similar among the three time periods. Importantly, overall useable blastocyst rate (day 5-7) remained within control limits (52%) for all three periods, indicating that the overall rate alone may not sufficiently monitor embryology laboratory performance. This study validates a statistical KPI monitoring system to provide systematic, early detection of culture condition shifts in ART laboratories. Useable day 5 blastocyst rate is identified as an important KPI, which complements overall useable blastocyst rate (day 5-7).

Human Age and Gender Prediction Based on Neural Networks and Three Sigma Control Limits

ABSTRACTA person’s face provides a lot of information such as age, gender, and identity. Faces play an important role in the estimation/prediction of the age and gender of persons, just by looking at their face. Perceiving human faces and modeling the distinctive features of human faces that contribute most toward face recognition are some of the challenges faced by computer vision and psychophysics researchers. There are many methods have been proposed in the literature for the facial features for age and gender classification. In this research, an attempt is made to classify human age and gender using feed forward propagation neural networks in coarser level. Further final classification is done using 3-sigma control limits in finer level. Proposed approach efficiently classifies three age groups including children, middle-aged adults, and old-aged adults. Similarly two gender groups classified into male and female by the proposed method.The performance of the system is further improved by employing multiple hierarchical decision using three sigma control limits applied on the output of the neural network classifier. The mean and standard deviation has been considered on the output generated from the neural network classifier, and three sigma control limits has been applied to define the range of values for the specific category of age and gender. The efficiency of the system is demonstrated through the experimental results using benchmark database images.

Monitoring the Process Mean When Standards Are Unknown: A Classic Problem Revisited

One of the most common applications in statistical process monitoring is the use of control charts to monitor a process mean. In practice, this is often performed with a Shewhart chart along with a Shewhart R (or an S) chart. Thus, two charts are typically used together, as a scheme, each using the 3-sigma limits. Moreover, the process mean and standard deviation are often unknown and need to be estimated before monitoring can begin. We show that there are three major issues with this monitoring scheme described in most textbooks. The first issue is not accounting for the effects of parameter estimation, which is known to degrade chart performance. The second issue is the implicit assumption that the charting statistics are both normally distributed and, accordingly, using the 3-sigma limits. The third issue is multiple charting, because two charts are used, in this scheme, at the same time. We illustrate the deleterious effects of these issues on the in-control properties of the charting scheme and present a method for finding the correct charting constants taking proper account of these issues. Tables of the new charting constants are provided for some commonly used nominal in-control average run length values and different sample sizes. This will aid in implementing the charting scheme correctly in practice. Examples are given along with a summary and some conclusions. Copyright © 2015 John Wiley & Sons, Ltd.

ALMA OBSERVATIONS OF THE HOST GALAXY OF GRB 090423 ATz= 8.23: DEEP LIMITS ON OBSCURED STAR FORMATION 630 MILLION YEARS AFTER THE BIG BANG

We present rest-frame far-infrared (FIR) and optical observations of the host galaxy of GRB090423 at z=8.23 from the Atacama Large Millimeter Array (ALMA) and the Spitzer Space Telescope, respectively. The host remains undetected to 3-sigma limits of Fnu(222 GHz)<33 microJy and Fnu(3.6 micron)<81 nJy. The FIR limit is about 20 times fainter than the luminosity of the local ULIRG Arp220, and comparable to the local starburst M82. Comparing to model spectral energy distributions we place a limit on the IR luminosity of L_IR(8-1000 micron)<3e10 Lsun, corresponding to a limit on the obscured star formation rate of SFR_IR<5 Msun/yr; for comparison, the limit on the unobscured star formation rate from Hubble Space Telescope rest-frame UV observations is SFR_UV<1 Msun/yr. We also place a limit on the host galaxy stellar mass of <5e7 Msun (for a stellar population age of 100 Myr and constant star formation rate). Finally, we compare our millimeter observations to those of field galaxies at z>4 (Lyman break galaxies, Ly-alpha emitters, and submillimeter galaxies), and find that our limit on the FIR luminosity is the most constraining to date, although the field galaxies have much larger rest-frame UV/optical luminosities than the host of GRB090423 by virtue of their selection techniques. We conclude that GRB host galaxies at z>4, especially those with measured interstellar medium metallicities from afterglow spectroscopy, are an attractive sample for future ALMA studies of high redshift obscured star formation.

An electronic prompt to improve hepatitis B virus screening prior to cancer treatment.

169 Background: Hepatitis B virus (HBV) reactivation is a potentially fatal complication of cancer therapy that is almost entirely preventable. Despite this, HBV screening rates remain low at many centers. We evaluated the effectiveness of an electronic prompt on HBV screening rates and compared this strategy with education alone. Methods: An education session on HBV reactivation was delivered to all oncology staff at two large, academic oncology centers in the fall of 2010. At one center (study center) an electronic prompt was also introduced. The electronic prompt reminded physicians to screen for HBV when booking a new patient’s first chemotherapy and automatically trigged an electronic order for HBsAg if the physician assented. The prompt was not implemented at the second (control) center. The primary endpoint was the rate of HBV screening. Actual HBV screening rates were determined in both centers for 10 months prior to and for 12 months following the interventions. HBV screening rates were assessed and compared with process control charts (p-charts); 3-sigma limits were employed to define special cause variation. Results: 6,116 new patients received their first chemotherapy during the study period (2,095 study center; 4,021 control center). In the pre-prompt period, the screening rate was stable at 16% at the study center and 25% in the control center. In the prompt period, the screening rate increased to 62% at the study center and was unchanged at 25% in the control center. Special cause variation suggesting a non-random improvement in HBV screening rate was detected at the Study Center two months after the introduction of the electronic prompt. Conclusions: An electronic prompt increased the rate of HBV screening, however screening rates remained relatively low. Education sessions did not appear to improve the HBV screening rate.

Extending a double sampling control chart for non-conforming proportion in high quality processes to the case of small samples

When production processes reach high quality standards they are known as high quality processes. In this situation, the conventional p charts (based on 3-sigma limits) used for monitoring non-conforming products have serious drawbacks in detecting changes in p due to excess of false alarm risk. In a previous paper, the authors showed a new p chart that provides a large improvement over the usual p chart in these situations. In this paper, authors propose a new corrected version of a double sampling (DS) control chart for monitoring the proportion p of non-conforming presented in the literature for large samples, in order to extend its applicability to the case of small samples. This procedure offers better statistical efficiency (in terms of the average run length) than the previous p charts, without increasing the sampling. Tables are provided to aid in the choice of DS parameters. The benefits of the corrected version of a DS chart for monitoring high-quality processes are illustrated with real data.

Optical and infrared polarimetry of the transient LMXB Centaurus X-4 in quiescence

We present the first optical and infrared polarimetric study of the low mass transient X-ray binary Cen X-4 during its quiescent phase. This work is aimed to search for an intrinsic linear polarisation component in the system emitted radiation that might be due, e.g., to synchrotron emission from a compact jet, or to Thomson scattering with free electrons in an accretion disc. Multiband (BVRI) optical polarimetric observations were obtained during two nights in 2008 at the ESO La Silla 3.6 m telescope (EFOSC2) in polarimetric mode. These observations cover about the 30% of the 15.1 hours orbital period. J-band observations were obtained in 2007 with the NICS (TNG) instrument at La Palma, for a totality of 1 hour observation. We obtained 3-sigma upper limits to the polarisation degree in all the optical bands, with the most constraining one being in the I-band (P<0.5%). No phase-correlated variability has been noticed in all the filters. The J-band observations provided a 6% upper limit on the polarisation level. The constraining upper limits to the polarisation in the optical allowed us to evaluate the contribution of the possible emission of a relativistic particles jet to the total system radiation to be less then the 10%. This is in agreement with the observation of a spectral energy distribution typical of a single black body of a K-spectral type main sequence star irradiated from the compact object. Due to the low S/N ratio it was not possible to investigate the possible dependency of the polarisation degree from the wavelength, that could be suggestive of polarisation induced by Thomson scattering of radiation with free electrons in the outer part of the accretion disc. Observations with higher S/N ratio are required to examine in depth this hypothesis, searching for significant phase-correlated variability.

PROTOPLANETARY DISK MASSES FROM STARS TO BROWN DWARFS

We present SCUBA-2 850um observations for 7 very low mass stars (VLMS) and brown dwarfs (BDs): 3 in Taurus, 4 in the TWA, and all classical T Tauri (cTT) analogs. We detect 2 of the 3 Taurus disks, but none of the TWA ones. Our 3sigma limits correspond to a dust mass of 1.2 MEarth in Taurus and a mere 0.2 MEarth in the TWA (3--10x deeper than previous work). We combine our data with other sub-mm/mm surveys of Taurus, rho Oph and the TWA to investigate trends in disk mass and grain growth during the cTT phase. We find : (1) The minimum disk outer radius required to explain the upper envelope of sub-mm/mm fluxes is 100 AU for intermediate-mass stars, solar-types and VLMS, and 20 AU for BDs. (2) While the upper envelope of disk masses increases with Mstar from BDs to VLMS to solar-types, no increase is seen from solar-type to intermediate-mass stars. We propose this is due to enhanced photoevaporation around intermediate masses. (3) Many disks around Taurus and rho Oph intermediate-mass and solar-type stars evince an opacity index beta of 0--1, indicating large grains. Of the only four VLMS/BDs in these regions with multi-wavelength data, three are consistent with large grains, though optically thick disks are not ruled out. (4) For the TWA VLMS (TWA 30A, B), combining our fluxes with Mdot and ages suggests substantial grain growth by 10 Myr. The degree of grain growth in the TWA BDs (2M1207A, SSPM1102) remains largely unknown. (5) A Bayesian analysis shows that mean(log[Mdisk/Mstar]) = -2.4, roughly constant all the way from intermediate-mass stars to VLMS/BDs, and (6) the disk mass in close solar-type Taurus binaries is significantly lower than in singles (by a factor of 10), while that in wide solar-type Taurus binaries is closer to that in singles (lower by a factor of 3). (7) We discuss the implications for planet formation, and for the dependence of Mdot on Mstar.