Overestimating Outcome Rates: Statistical Estimation When Reliability Is Suboptimal

To demonstrate how failure to account for measurement error in an outcome (dependent) variable can lead to significant estimation errors and to illustrate ways to recognize and avoid these errors. Data Sources . Medical literature and simulation models. Study Design/Data Collection . Systematic review of the published and unpublished epidemiological literature on the rate of preventable hospital deaths and statistical simulation of potential estimation errors based on data from these studies. Principal Findings . Most estimates of the rate of preventable deaths in U.S. hospitals rely upon classifying cases using one to three physician reviewers (implicit review). Because this method has low to moderate reliability, estimates based on statistical methods that do not account for error in the measurement of a “preventable death” can result in significant overestimation. For example, relying on a majority rule rating with three reviewers per case (reliability ∼0.45 for the average of three reviewers) can result in a 50–100 percent overestimation compared with an estimate based upon a reliably measured outcome (e.g., by using 50 reviewers per case). However, there are statistical methods that account for measurement error that can produce much more accurate estimates of outcome rates without requiring a large number of measurements per case. Conclusion . The statistical principles discussed in this case study are critically important whenever one seeks to estimate the proportion of cases belonging to specific categories (such as estimating how many patients have inadequate blood pressure control or identifying high-cost or low-quality physicians). When the true outcome rate is low (<20 percent), using an outcome measure that has low-to-moderate reliability will generally result in substantially overestimating the proportion of the population having the outcome unless statistical methods that adjust for measurement error are used.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74896/1/j.1475-6773.2006.00661.x.pd

MOTIVASI, TINGKAT PENDIDIKAN, DAN STATUS SOSIAL EKONOMI DIHUBUNGKAN DENGAN HASIL-HASIL PELATIHAN DAN PRAKTEK KETERAMPILAN KERJA PADA PELATIHAN CALON BABY SITTER: Studi Analisa Data terhadap Calon Baby Sitter di Panti Penitipan Bayi "Ade Irma Suryani Nasution" Medan

Fokus permasalahan yang diangkat dalam Tesis ini adalah Motivasi, tingkat pendidikan dan status sosial ekonomi dihubungkan dengan hasil-hasil pelatihan dan praktek keterampilan kerja calon baby sitter. Karena keempat faktor ini merupakan suatu pernyataan yang abstrak maka perlu dijabarkan ke dalam indikator variabel sesuai dengan tujuan penelitian yaitu untuk mengetahui tingkat motivasi, tingkat pendidikan, status sosial ekonomi yang dihubungkan dengan hasil-hasil pelatihan dan praktek keterampilan kerja calon baby sitter, dan untuk menguji adakah hubungan antara keempat variabel tersebut. Penelitian ini berlokasi di Jalan T. Cik Ditiro, Kecamatan Medan Baru - Medan. Teori yang digunakan di dalam penelitian ini adalah teori-teori tentang Motivasi yang dikutip dari pendapat W.J.S. Poerwodarminta (1982: 655), Mc. Clelland (1987: 51) tentang "Social motives theory", dimana padadasarnya semua pekerjaan membutuhkan motivasi yang cukup bagi setiap orang untuk melaksanakan suatu pekerjaan dengan berhasil. Selanjutnya teori-teori tentang Tingkat Pendidikan yang dikutip dari pendapat Moh. Surya (1990: 20) tentang taman kanak-kanak, Kartini Kartono (1986: 139), tentang tingkat Sekolah Dasar, Zulkifli L (1987: 87), tentang tingkat SLTP dan tingkat SLTAdan universitas, dimana tinggi rendahnya pendidikan seseorang akan mencerminkan tingkat pengetahuan dan sikap serta prilakunya. Teori-teori tentang Status Sosial Ekonomi yang dikutip dari pendapat Mayor Polak (1979), Miller (1964) dan SC. Utami Munandar (1982) dimana tinggi-rendahnya status sosial ekonomi orang tua cenderung menentukan perbedaan tanggung jawab orang tua pada anaknya. Teoriteori tentang training oleh Sikula (1976), Mulyanan Sugandi (1993), dimana dijelaskan bahwa program latihan kerja dapat mempertinggi kemampuan kerja dengan mengembangkan cara-cara berpikir dan bertindak yang tepat serta memiliki pengetahuan tentang tugas. Penelitian ini menggunakan metode deskriptif dengan tehnik studi Analisis data dan juga digolongkan ke dalam penelitian eksplanasi (explanatory research), karena penelitian ini juga berupaya meneliti hubungan variabel yang dihipotesiskan. Penelitian ini menggunakan pendekatan kuantitatif dengan perhitungan statistik non-parametrik. Sampel dalam penelitian ini adalah sampel total, yaitu 50 orang responden yang mengikuti latihan calon baby sitter di Panti Perawatan dan Penitipan Bayi "ADE IRMA SURYANI NASUTION" Medan. Teknik analisis data yang digunakan adalah statistik non-parametrik. Alat pengumpul data yang dipergunakan untuk variabel independen adalah Kuesioner yang terlebih dahulu diuji validitas dan reliabilitasnya, sedangkan alat pengumpul data untuk variabel dependen adalah dokumentasi. Setelah dilakukan pengolahan dan analisa data diperoleh hasil penelitian sebagai berikut: Pertama; Hasil perhitungan statistik Yule's Qmenunjukkan QxiYa = 0,6 dan chi kuadratnya = 3,853 jadi dapat ditarik kesimpulan terdapat hubungan positif yang mantap dan signifikan antara motivasi dengan hasil-hasil pelatihan dimana *2 hitung 3,853 > %2 urn 3,84 pada dk = 1 dengan taraf kepercayaan 0,95% dan hasil perhitungan statistik Yule's Qmenunjukkan QxiYb = 0,54 dan uji chi kuadratnva = 3,4. "rial ini mengandung makna bahwa terdapat hubungan positif yang mantap serta berkonstribusi antara motivasi dengan praktek keterampilan kerja, dimana y? ^ung =3,4 <X2 ,abe. 3,84 pada dk = 1dengan taraf kepercayaan 0,95%. Kedua: Hasil perhitungan statistik Yule's Qmenunjukkan QX2Ya - - 0,45 dan chi kuadratnva = 1,86 makna yang dapat ditarik dari analisis ini yaitu terdapat hubungan negatif vang sedang tetapi tidak signifikan antara tingkat pendidikan dengan hasil-hasil pelatihan dimana %2 wtung =1,86 <X2 tabci 3,84. Sedangkan untuk perhitungan statistik Yule's QQX2Yb =- 0,25 dan chi kuadratnya =0,52. Ini dapat diartikan bahwa terdapat hubungan negatif yang rendah dan tidak signifikan antara tingkat pendidikan dengan praktek keterampilan kerja, dimana %2 wtung =0,52 < X2tabei 384 pada dk =1dengan taraf kepercayaan 0,95%. Ketiga Hasil perhitungan statistik Yule's Qmenunjukkan Qxsva =0,153 dan uji chi kuadratnya =0,23 dapat diartikan bahwa terdapat hubungan positif yang rendah tetapi tidak signifikan antara status sosial ekonomi dengan hasil-hasil pelatihan dimana x hhung = 0,23 < X2 .abei 3,84 pada dk = 1 dengan taraf kepercayaan 0,95%. Sedangkan untuk perhitungan statistik Yule's Qmenunjukkan Qxavb =0,4 dan uji chi kuadratnya - 175 Ini dapat diartikan bahwa terdapat hubungan positif yang sedang antara status sosial ekonomi dengan praktek keterampilan kerja tetapi tidak signifikan, dimana X2 hitung =1J <X2 tabei 3,84 pada dk =1dengan taraf kepercayaan 0,95%. Dari temuan penelitian ini dapat disimpulkan bahwa semakin tinggi motivasi calon baby sitter untuk mengikuti pelatihan maka semakin tinggi hasilhasil pelatihan yang akan diperolehnya. Begitu juga di dalam memperoleh nilai praktek, motivasi seseorang sangat berpengaruh atau konstnbusi yang dibenkan oleh motivasi terhadap nilai praktek sangat besar. Sedangkan untuk tingkat pendidikan dapat disimpulkan bahwa untuk menjadi seorang baby sitter tidak dibutuhkan orang-orang yang berpendidikan tinggi cukup hanya pada tingkat pendidikan SLTP dan SLTA saja, hal ini dapat dibuktikan dan hasil penelitian yang dilakukan tidak terdapat hubungan yang signifikan antara tingkat pendidikan dengan hasil-hasil pelatihan (nilai teori), begitu juga untuk hubungan antara tingkat pendidikan dengan praktek keterampilan kerja (nilai praktek) tidak berkorelasi, artinya semakin tinggi tingkat pendidikan seseorang ada kecenderungan semakin baik pelaksanaan praktek keterampilan kerjanya. Selanjutnya yang berkaitan dengan status sosial ekonomi orang tua calon baby sitter sama sekali tidak mempengaruhi kesempatan bagi calon baby sitter untuk berprestasi, atau dengan kata lain walaupun sebagian besar orang tua calon baby sitter termasuk dalam status sosial ekonomi kategori rendah tetapi tidak menutup kemungkinan bagi anaknya (calon baby sitter) yang mengikuti pelatihan untuk memihki nilai teon dan praktek keterampilan kerja yang tinggi

Synchrony of change in depressive symptoms, health status, and quality of life in persons with clinical depression

BACKGROUND: Little is known about longitudinal associations among measures of depression, mental and physical health, and quality of life (QOL). We followed 982 clinically depressed persons to determine which measures changed and whether the change was synchronous with change in depressive symptoms. METHODS: Data were from the Longitudinal Investigation of Depression Outcomes (LIDO). Depressive symptoms, physical and mental health, and quality of life were measured at baseline, 6 weeks, 3 months, and 9 months. Change in the measures was examined over time and for persons with different levels of change in depressive symptoms. RESULTS: On average, all of the measures improved significantly over time, and most were synchronous with change in depressive symptoms. Measures of mental health changed the most, and physical health the least. The measures of change in QOL were intermediate. The 6-week change in QOL could be explained completely by change in depressive symptoms. The instruments varied in sensitivity to changes in depressive symptoms. CONCLUSION: In clinically depressed persons, measures of physical health, mental health, and quality of life showed consistent longitudinal associations with measures of depressive symptoms

The impact of attrition on the representativeness of cohort studies of older people

Background: There are well-established risk factors, such as lower education, for attrition of study participants. Consequently, the representativeness of the cohort in a longitudinal study may deteriorate over time. Death is a common form of attrition in cohort studies of older people. The aim of this paper is to examine the effects of death and other forms of attrition on risk factor prevalence in the study cohort and the target population over time

Trajectories of self-rated health in people with diabetes: Associations with functioning in a prospective community sample

© 2013 Schmitz et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Self-rated health (SRH) is a single-item measure that is one of the most widely used measures of general health in population health research. Relatively little is known about changes and the trajectories of SRH in people with chronic medical conditions. The aims of the present study were to identify and describe longitudinal trajectories of self-rated health (SRH) status in people with diabetes. Methods: A prospective community study was carried out between 2008 and 2011. SRH was assessed at baseline and yearly at follow-ups (n=1288). Analysis was carried out through trajectory modeling. The trajectory groups were subsequently compared at 4 years follow-up with respect to functioning. Results: Four distinct trajectories of SRH were identified: 1) 72.2% of the participants were assigned to a persistently good SRH trajectory; 2) 10.1% were assigned to a persistently poor SRH trajectory; 3) mean SRH scores changed from good to poor for one group (7.3%); while 4) mean SRH scores changed from poor to medium/good for another group (10.4%). Those with a persistently poor perception of health status were at higher risk for poor functioning at 4 years follow-up than those whose SRH scores decreased from good to poor. Conclusions: SRH is an important predictor for poor functioning in diabetes, but the trajectory of SRH seems to be even more important. Health professionals should pay attention to not only SRH per se, but also changes in SRH over time.This work was supported by Operating Grant MOP-84574 from the Canadian Institutes of Health Research (CIHR). GG was supported by a doctoral fellowship from the CIHR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Measuring Success for a Future Vision: Defining Impact in Science Gateways/Virtual Research Environments

Scholars worldwide leverage science gateways/VREs for a wide variety of research and education endeavors spanning diverse scientific fields. Evaluating the value of a given science gateway/VRE to its constituent community is critical in obtaining the financial and human resources necessary to sustain operations and increase adoption in the user community. In this paper, we feature a variety of exemplar science gateways/VREs and detail how they define impact in terms of e.g., their purpose, operation principles, and size of user base. Further, the exemplars recognize that their science gateways/VREs will continuously evolve with technological advancements and standards in cloud computing platforms, web service architectures, data management tools and cybersecurity. Correspondingly, we present a number of technology advances that could be incorporated in next-generation science gateways/VREs to enhance their scope and scale of their operations for greater success/impact. The exemplars are selected from owners of science gateways in the Science Gateways Community Institute (SGCI) clientele in the United States, and from the owners of VREs in the International Virtual Research Environment Interest Group (VRE-IG) of the Research Data Alliance. Thus, community-driven best practices and technology advances are compiled from diverse expert groups with an international perspective to envisage futuristic science gateway/VRE innovations

Examining the BMI-mortality relationship using fractional polynomials

<p>Abstract</p> <p>Background</p> <p>Many previous studies estimating the relationship between body mass index (BMI) and mortality impose assumptions regarding the functional form for BMI and result in conflicting findings. This study investigated a flexible data driven modelling approach to determine the nonlinear and asymmetric functional form for BMI used to examine the relationship between mortality and obesity. This approach was then compared against other commonly used regression models.</p> <p>Methods</p> <p>This study used data from the National Health Interview Survey, between 1997 and 2000. Respondents were linked to the National Death Index with mortality follow-up through 2005. We estimated 5-year all-cause mortality for adults over age 18 using the logistic regression model adjusting for BMI, age and smoking status. All analyses were stratified by sex. The multivariable fractional polynomials (MFP) procedure was employed to determine the best fitting functional form for BMI and evaluated against the model that includes linear and quadratic terms for BMI and the model that groups BMI into standard weight status categories using a deviance difference test. Estimated BMI-mortality curves across models were then compared graphically.</p> <p>Results</p> <p>The best fitting adjustment model contained the powers -1 and -2 for BMI. The relationship between 5-year mortality and BMI when estimated using the MFP approach exhibited a J-shaped pattern for women and a U-shaped pattern for men. A deviance difference test showed a statistically significant improvement in model fit compared to other BMI functions. We found important differences between the MFP model and other commonly used models with regard to the shape and nadir of the BMI-mortality curve and mortality estimates.</p> <p>Conclusions</p> <p>The MFP approach provides a robust alternative to categorization or conventional linear-quadratic models for BMI, which limit the number of curve shapes. The approach is potentially useful in estimating the relationship between the full spectrum of BMI values and other health outcomes, or costs.</p

Cost calculation and prediction in adult intensive care: A ground-up utilization study

Publisher's copy made available with the permission of the publisherThe ability of various proxy cost measures, including therapeutic activity scores (TISS and Omega) and cumulative daily severity of illness scores, to predict individual ICU patient costs was assessed in a prospective “ground-up” utilization costing study over a six month period in 1991. Daily activity (TISS and Omega scores) and utilization in consecutive admissions to three adult university associated ICUs was recorded by dedicated data collectors. Cost prediction used linear regression with determination (80%) and validation (20%) data sets. The cohort, 1333 patients, had a mean (SD) age 57.5 (19.4) years, (41% female) and admission APACHE III score of 58 (27). ICU length of stay and mortality were 3.9 (6.1) days and 17.6% respectively. Mean total TISS and Omega scores were 117 (157) and 72 (113) respectively. Mean patient costs per ICU episode (1991 $AUS) were$6801 ($10311), with median costs of$2534, range $106 to$95,602. Dominant cost fractions were nursing 43.3% and overheads 16.9%. Inflation adjusted year 2002 (mean) costs were $9343 ($ AUS). Total costs in survivors were predicted by Omega score, summed APACHE III score and ICU length of stay; determination R2, 0.91; validation 0.88. Omega was the preferred activity score. Without the Omega score, predictors were age, summed APACHE III score and ICU length of stay; determination R2, 0.73; validation 0.73. In non-survivors, predictors were age and ICU length of stay (plus interaction), and Omega score (determination R2, 0.97; validation 0.91). Patient costs may be predicted by a combination of ICU activity indices and severity scores.J. L. Moran, A. R. Peisach, P. J. Solomon, J. Martinhttp://www.aaic.net.au/Article.asp?D=200403