13,594 research outputs found
A comparison of staff perceptions and student experiences of issues associated with university
A significant body of research (Yorke, 1999a; 1999b; 2000a; 2000b) has examined difficulties experienced by students who withdraw from university. However, less work has been undertaken around students who experience difficulties but choose to remain in their studies. Similarly, limited work has addressed how tutors and university support staff perceive difficulties associated with the student experience and whether these are in line with student accounts. The lack of research around university staff perceptions is surprising given that tutors must have a good knowledge of the student experience in order to be able to understand and support learning. The purpose of this study was twofold. Firstly, to examine what difficulties students reported experiencing during university and secondly, to ascertain if university staff knowledge of student difficulties were in line with student accounts. Using semi-structured interviews and an online questionnaire, staff and student perceptions of university difficulties were examined. Results showed that all students experienced difficulties whilst studying. It was generally found that university staff had a good knowledge of student difficulties. However, two types of difficulty were identified (related to university systems and experience of teaching) of which staff were less aware. Possible explanations for findings are offered along with recommendations as to how findings might influence a learning developer.
A note on the estimation of confidence intervals for cost-effectiveness when costs and effects are censored
<i>Background</i>. The relation between methodological advances in estimation of confidence intervals (CIs) for incremental cost-effectiveness ratios (ICER) and estimation of cost effectiveness in the presence of censoring has not been explored. The authors address the joint problem of estimating ICER precision in the presence of censoring.
<i>Methods</i>. Using patient-level data (n = 168) on cost and survival from a published placebo-controlled trial, the authors compared 2 methods of measuring uncertainty with censored data: 1)Bootstrap with censor adjustment (BCA); 2) Fieller’s method with censor adjustment (FCA). The authors estimate the FCA over all possible values for the correlation (p) between costs and effects (range= –1 to +1) and also examine the use of the correlation between cases without censoring adjustment (i.e., simple time-on-study) for costs and effects as an approximation for.
<i>Results</i>. Using time-on-study, which considers all
censored observations as responders (deaths), yields 0.64
life-years gained at an additional cost of 87.9 for a cost per life-year of 137 (95% CI by bootstrap –5.9 to 392). Censoring adjustment corrects for the bias in the time-on-study approach and reduces the cost per life-year estimate to 132 (=72/0.54). Confidence intervals with censor adjustment were approximately 40% wider than the base-case without adjustment. Using the Fieller method with an approximation of based on the uncensored cost and effect correlation provides a 95% CI of (–48 to 529), which is very close to the BCA interval of (–52 to 504).
<i>Conclusions</i>. Adjustment for censoring is necessary in cost-effectiveness studies to obtain unbiased estimates of ICER with appropriate uncertainty limits. In this study, BCA and FCA methods, the latter with approximated covariance, are simple to compute and give similar confidence intervals
HI 21cm observations of the PG1216+069 sub-DLy-alpha absorber field at z=0.00632
The Westerbork Synthesis Radio Telescope finds a weak 21cm line emission
feature at the coordinates (RA-Dec-velocity) of the sub-Damped Lyman-alpha
absorber observed at z_abs=0.00632 in the spectrum of PG1216+069. The emission
feature, WSRT-J121921+0639, lies within 30" of the quasar sightline, is
detected at 99.8% (3 sigma) confidence level, has M_HI between 5 and 15x10^6
M_solar, and has velocity spread between 20 and 60 km/s. Other HI emitters in
the field include VCC297 at a projected distance of 86/h_75 kpc and a
previously unreported HI cloud, WSRT-J121919+0624 at 112/h_75 kpc with M_HI ~
3x10^8 M_solar. The optically identified, foreground galaxy that is closest to
the quasar sightline appears to be VCC339 (~L*/25) at 29/h_75 kpc and velocity
offset 292 km/s . A low surface brightness galaxy with the HI mass of the
sub-DLA absorber WSRT-J121921+0639 would likely have m_B ~ 17, and its diffuse
optical emission would need to compete with the light of both the background
QSO and a brighter foreground star ~10" from the QSO sight line.Comment: 10 pages, 2 figures, accepted for publication in ApJLet
Thinking outside the box: recent advances in the analysis and presentation of uncertainty in cost-effectiveness studies
As many more clinical trials collect economic information within their study design, so health economics analysts are increasingly working with patient-level data on both costs and effects. In this paper, we review recent advances in the use of statistical methods for economic analysis of information collected alongside clinical trials. In particular, we focus on the handling and presentation of uncertainty, including the importance of estimation rather than hypothesis testing, the use of the net-benefit statistic, and the presentation of cost-effectiveness acceptability curves. We also discuss the appropriate sample size calculations for cost-effectiveness analysis at the design stage of a study. Finally, we outline some of the challenges for future research in this area—particularly in relation to the appropriate use of Bayesian methods and methods for analyzing costs that are typically skewed and often incomplete
Probabilistic analysis of cost-effectiveness models: choosing between treatment strategies for gastroesophageal reflux disease
When choosing between mutually exclusive treatment options, it is common to construct a cost-effectiveness frontier on the cost-effectiveness plane that represents efficient points from among the treatment choices. Treatment options internal to the frontier are considered inefficient and are excluded either by strict dominance or by appealing to the principle of extended dominance. However, when uncertainty is considered, options excluded under the baseline analysis may form part of the cost-effectiveness frontier. By adopting a Bayesian approach, where distributions for model parameters are specified, uncertainty in the decision concerning which treatment option should be implemented is addressed directly. The approach is illustrated using an example from a recently published cost-effectiveness analysis of different possible treatment strategies for gastroesophageal reflux disease.It is argued that probabilistic analyses should be encouraged because they have potential to quantify the strength of evidence in favor of particular treatment choices
Estimating the cost-effectiveness of fluticasone propionate for treating chronic obstructive pulmonary disease in the presence of missing data
Objectives: To explore the cost-effectiveness of fluticasone propionate (FP) for the treatment of chronic obstructive pulmonary disease (COPD), we estimated costs and qualityadjusted life-years (QALYs) over 3 years, based on an economic appraisal of a previously reported clinical trial
(Inhaled Steroids in Obstructive Lung Disease in Europe [ISOLDE]).
Methods: Seven hundred forty-two patients enrolled in the ISOLDE trial who received either FP or placebo had data available on health-care costs and quality of life over the period of the study. The SF-36-based utility scores for quality
of life were used to calculate QALYs. A combined imputation and bootstrapping procedure was employed to handle missing data and to estimate statistical uncertainty in the estimated
cumulative costs and QALYs over the study period.
The imputation approach was based on propensity scoring and nesting this approach within the bootstrap ensured that multiple imputations were performed such that statistical estimates included imputation uncertainty.
Results: Complete data were available on mortality within the follow-up period of the study and a nonsignificant trend toward improved survival of 0.06 (95% confidence interval [CI] –0.01 to 0.15) life-years was observed. In an analysis based on a propensity scoring approach to missing data we estimated the incremental costs of FP versus placebo to be £1021 (95% CI £619–1338) with an additional effect of 0.11 QALYs (CI 0.04–0.20). Cost-effectiveness estimates
for the within-trial period of £17,700 per life-year gained (£6900 to ∞) and £9500 per QALY gained (CI £4300–26,500) were generated that include uncertainty due to the imputation process. An alternative imputation approach did
not materially affect these estimates.
Conclusions: Previous analyses of the ISOLDE study
showed significant improvement on disease-specific health status measures and a trend toward a survival advantage for treatment with FP. This analysis shows that joint considerations
of quality of life and survival result in a substantial increase in QALYs favoring treatment with FP. Based on these data, the inhaled corticosteroid FP appears costeffective for the treatment of COPD. Confirmation or refutation
of this result may be achieved once the Towards a
Revolution in COPD Health (TORCH) study reports, a large randomized controlled trial powered to detect mortality changes associated with the use of FP alone, or in combination with salmeterol, which is also collecting resource use and utility data suitable for estimating cost-effectiveness
Spin detection at elevated temperatures using a driven double quantum dot
We consider a double quantum dot in the Pauli blockade regime interacting
with a nearby single spin. We show that under microwave irradiation the average
electron occupations of the dots exhibit resonances that are sensitive to the
state of the nearby spin. The system thus acts as a spin meter for the nearby
spin. We investigate the conditions for a non-demolition read-out of the spin
and find that the meter works at temperatures comparable to the dot charging
energy and sensitivity is mainly limited by the intradot spin relaxation.Comment: 8 pages, 6 figure
Paleoseismic and Slip-Rate Observations along the Honey Lake Fault Zone, Northeastern California, USA
The Honey Lake fault is a major strike-slip fault in northeastern California that accommodates northwest-directed right-lateral shear in the northern Walker Lane. We reexamine the fault’s paleoseismic history and slip rate by evaluating a natural stream bank exposure of the fault and offset terrace riser. Structural and stratigraphic relations within the modern stream cut, radiocarbon ages, and a detailed topographic survey of the offset terrace riser are used to estimate a Holocene fault slip rate of 1.7–0.6 mm/yr or more. We also interpret the occurrence of at least four surface-rupturing earthquakes during the last 7025 calendar years before present (B.P.). Three of the surface-rupturing earthquakes occurred prior to 4670 calendar years B.P. and have interevent times that range between 730 and 990 yr. The stratigraphic record is limited after ~4670 calendar years B.P., and records evidence for at least one more subsequent surface-rupturing earthquake
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