Biostatistics Commons^™

Realistic Spiking Neuron Statistics In A Population Are Described By A Single Parametric Distribution, Lauren Crow 9370373

Undergraduate Research Posters

The spiking of activity of neurons throughout the cortex is random and complicated. This complicated activity requires theoretical formulations in order to understand the underlying principles of neural processing. A key aspect of theoretical investigations is characterizing the probability distribution of spiking activity. This study aims to better understand the statistics of the time between spikes, or interspike interval, in both real data and a spiking model with many time scales. Exploration of the interspike intervals of neural network activity can provide a better understanding of neural responses to different stimuli. We consider different parametric distribution fitting techniques to characterize …

Meta-Analysis Of Gene Expression Studies, Umaporn Siangphoe

Theses and Dissertations

Combining effect sizes from individual studies using random-effects models are commonly applied in high-dimensional gene expression data. However, unknown study heterogeneity can arise from inconsistency of sample qualities and experimental conditions. High heterogeneity of effect sizes can reduce statistical power of the models. We proposed two new methods for random effects estimation and measurements for model variation and strength of the study heterogeneity. We then developed a statistical technique to test for significance of random effects and identify heterogeneous genes. We also proposed another meta-analytic approach that incorporates informative weights in the random effects meta-analysis models. We compared the proposed …

Controlling For Confounding When Association Is Quantified By Area Under The Roc Curve, Hadiza I. Galadima

Theses and Dissertations

In the medical literature, there has been an increased interest in evaluating association between exposure and outcomes using nonrandomized observational studies. However, because assignments to exposure are not done randomly in observational studies, comparisons of outcomes between exposed and non-exposed subjects must account for the effect of confounders. Propensity score methods have been widely used to control for confounding, when estimating exposure effect. Previous studies have shown that conditioning on the propensity score results in biased estimation of odds ratio and hazard ratio. However, there is a lack of research into the performance of propensity score methods for estimating the …

Characteristics Associated With Willingness To Participate In A Randomized Controlled Behavioral Clinical Trial Using Home-Based Personal Computers And A Webcam, Hiroko H. Dodge, Yuriko Katsumata, Jian Zhu, Nora Mattek, Molly Bowman, Mattie Gregor, Katherine Wild, Jeffrey A Kaye

Biostatistics Faculty Publications

BACKGROUND: Trials aimed at preventing cognitive decline through cognitive stimulation among those with normal cognition or mild cognitive impairment are of significant importance in delaying the onset of dementia and reducing dementia prevalence. One challenge in these prevention trials is sample recruitment bias. Those willing to volunteer for these trials could be socially active, in relatively good health, and have high educational levels and cognitive function. These participants' characteristics could reduce the generalizability of study results and, more importantly, mask trial effects. We developed a randomized controlled trial to examine whether conversation-based cognitive stimulation delivered through personal computers, a webcam …

Statistical Inference For The Mean Outcome Under A Possibly Non-Unique Optimal Treatment Strategy, Alexander R. Luedtke, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

We consider challenges that arise in the estimation of the value of an optimal individualized treatment strategy defined as the treatment rule that maximizes the population mean outcome, where the candidate treatment rules are restricted to depend on baseline covariates. We prove a necessary and sufficient condition for the pathwise differentiability of the optimal value, a key condition needed to develop a regular asymptotically linear (RAL) estimator of this parameter. The stated condition is slightly more general than the previous condition implied in the literature. We then describe an approach to obtain root-n rate confidence intervals for the optimal value …

Mediation Analysis Of Gestational Age, Congenital Heart Defects, And Infant Birth-Weight, Adane F. Wogu, Christopher A. Loffredo, Ionut Bebu, George Luta

GW Biostatistics Center

Background

In this study we assessed the mediation role of the gestational age on the effect of the infant’s congenital heart defects (CHD) on birth-weight.

Methods

We used secondary data from the Baltimore-Washington Infant Study (1981–1989). Mediation analysis was employed to investigate whether gestational age acted as a mediator of the association between CHD and reduced birth-weight. We estimated the mediated effect, the mediation proportion, and their corresponding 95% confidence intervals (CI) using several methods.

Results

There were 3362 CHD cases and 3564 controls in the dataset with mean birth-weight of 3071 (SD = 729) and 3353 (SD = 603) …

A More Efficient Nonparametric Test Of Symmetry Based On Overlapping Coefficient, Hani M. Samawi, Robert L. Vogel

Biostatistics: Faculty Publications

In this paper we provide a more efficient nonparametric test of symmetry based on the empirical overlap coefficient using kernel density estimation applied to an extreme order statistics, namely extreme ranked set sampling. Our simulation investigation reveals that our proposed test of symmetry is at least as powerful as currently available tests of symmetry. Intensive simulation is conducted to examine the power of the proposed test. An illustration is provided using cardiac output and body weight of neonates in a neonatal intensive care unit.

Methods For Identifying Regions Of Brain Activation Using Fmri Meta-Data, Meredith A. Ray

Theses and Dissertations

Functional neuroimaging is a relatively young discipline within the neurosciences that has led to significant advances in our understanding of the human brain and progress in neuroscientific research related to public health. Accurately identifying activated regions in the brain showing a strong association with an outcome of interest is crucial in terms of disease prediction and prevention. Functional magnetic resonance imaging (fMRI) is the most widely used method for this type of study as it has the ability to measure and identify the location of changes in tissue perfusion, blood oxygenation, and blood volume. In practice, the three-dimensional brain locations …

Simulation Based Evaluation Of Multiscale Small Area Health Models, Purbasha Dasgupta

Theses and Dissertations

The effects of scale on the analysis of spatial data, often referred to as the modifiable areal unit problem in spatial studies, is one of the issues often encountered in small area health models. These spatial effects of scale are also seen in the areas of disease mapping where data are usually available in counts. Often there is a need to consider the different scales of aggregation that exist within count data, since inferences based on analyses can vary if we change the definition of the unit of analysis. This thesis provides a framework that describes the distribution of relative …

Access To Hiv Prevention And Care For Hiv-Exposed And Hiv-Infected Children: A Qualitative Study In Rural And Urban Mozambique, Caroline De Schacht, Carlota Lucas, Caterina Mboa, Michelle Gill, Eugenia Macasse, Stelio A. Dimande, Emily A. Bobrow, Laura Guay

Epidemiology Faculty Publications

Background Follow-up of HIV-exposed children for the delivery of prevention of mother-to-child transmission services and for early diagnosis and treatment of HIV infection is critical to their survival. Despite efforts, uptake of postnatal care for these children remains low in many subSaharan African countries. Methods A qualitative study was conducted in three provinces in Mozambique to identify motivators and barriers to improve uptake of and retention in HIV prevention, care and treatment services for HIV-exposed and HIV-infected children. Participant recommendations were also gathered. Individual interviews (n=79) and focus group discussions (n=32) were conducted with parents/caregivers, grandmothers, community leaders and health …

Prognostic Value Of Lymphocyte Vascular Density And E-Cadherin In Inflammatory Breast Cancer, Paul H. Levine, Heather J. Hoffman, Audra Macneil, Salman Hashmi, Sherry X. Yang, Stephen Hewitt, Kenneth L. Van Golen, Sandra M. Swain

Epidemiology Faculty Publications

Background: We recently evaluated four laboratory assays, vascular endothelial growth factor D (VEGF-D), E-cadherin, lymphatic vessel density (LVD) measured by podoplanin, and intra-lymphatic tumor emboli (ILTE), which showed notable differences between inflammatory breast cancer (IBC) and non-inflammatory locally advanced breast cancer (LABC). In this study we investigated the potential of the three most quantitatively measured markers, E-cadherin, LVD and VEGF-D, to predict survival in the IBC patients.

Materials and Methods: This study involved the 100 cases identified in the Inflammatory Breast Cancer Registry (IBCR) whose tumors were previously evaluated for the four assays noted above. Living patients were recontacted and …

The Effectiveness Of Teleglaucoma Versus In-Patient Examination For Glaucoma Screening: A Systematic Review And Meta-Analysis, Sera-Melisa Thomas, Maya M Jeyaraman, Maya Jeyaraman, William G Hodge, Cindy Hutnik, John Costella, Monali S Malvankar-Mehta

Epidemiology and Biostatistics Publications

BACKGROUND: Glaucoma is the leading cause of irreversible visual impairment in the world affecting 60.5 million people worldwide in 2010, which is expected to increase to approximately 79.6 million by 2020. Therefore, glaucoma screening is important to detect, diagnose, and treat patients at the earlier stages to prevent disease progression and vision loss. Teleglaucoma uses stereoscopic digital imaging to take ocular images, which are transmitted electronically to an ocular specialist. The purpose is to synthesize literature to evaluate teleglaucoma, its diagnostic accuracy, healthcare system benefits, and cost-effectiveness.

METHODS: A systematic search was conducted to help locate published and unpublished studies. …

Identifying Change Points In A Covariate Effect On Time-To-Event Analysis With Reduced Isotonic Regression, Yong Ma, Yinglei Lai, John M. Lachin

GW Biostatistics Center

Isotonic regression is a useful tool to investigate the relationship between a quantitative covariate and a time-to-event outcome. The resulting non-parametric model is a monotonic step function of a covariate X and the steps can be viewed as change points in the underlying hazard function. However, when there are too many steps, over-fitting can occur and further reduction is desirable. We propose a reduced isotonic regression approach to allow combination of small neighboring steps that are not statistically significantly different. In this approach, a second stage, the reduction stage, is integrated into the usual monotonic step building algorithm by comparing …

Overview Of Inference About Roc Curve In Medical Diagnosis, Jingjing Yin

Biostatistics: Faculty Publications

Medical diagnosis aims to identify diseased individuals through the evaluation of the measurements of some biomarkers by performing a diagnostic test based on some biomarker measurements. Biomarkers are measured on either discrete or continuous scale and continuous biomarkers are utilized more often in medical practice. This article introduces the most popular tool for evaluating continuous biomarkers: the Receiver Operating Characteristic (ROC) curve.

Assessing The Social And Ecological Factors That Influence Childhood Overweight And Obesity, Katie Callahan

Electronic Theses and Dissertations

The prevalence of childhood overweight and obesity is increasing at an alarming rate in the United States. Currently more than 1 in 3 children aged 2-19 are overweight or obese. This is of major concern because childhood overweight and obesity leads to chronic conditions such as type II diabetes and tracks into adulthood, where more severe adverse health outcomes arise. In this study I used the premise of the social ecological model (SEM) to analyze the common levels that a child is exposed to daily; the intrapersonal level, the interpersonal level, the school level, and the community level to better …

Pengaruh Rejimen Terhadap Ketidakpatuhan Berobat Tuberkulosis, Rizka Nur Fadila, Pandu Riono

Kesmas

Beban tuberkulosis di Indonesia termasuk lima tertinggi di dunia. Temuan kasus dan pengobatan adalah pilar utama program penanggulangan tuberkulosis. Survei nasional menunjukkan peningkatan penggunaan rejimen tidak standar dari 16,8% (2010) menjadi 55,6% (2013). Peningkatan penggunaan rejimen tidak standar diduga berpengaruh terhadap ketidakpatuhan berobat. Penelitian ini bertujuan untuk mempelajari ketidakpatuhan berobat pada orang dengan tuberkulosis yang menerima rejimen tidak standar dan rejimen standar. Penelitian menggunakan data sekunder Riset Kesehatan Dasar 2010. Analisis logistik multivariabel dilakukan pada sampel 971 orang dengan tuberkulosis yang selesai mendapatkan pengobatan. Hasil penelitian menunjukkan ada kecenderungan orang dengan tuberkulosis yang menerima rejimen tidak standar memiliki ketidakpatuhan berobat …

Annual Parasite Incidence Malaria Di Kabupaten Banyumas, Dwi Sarwani Sri Rejeki, Ruthi Armita Sari, Nunung Nurhayati

Kesmas

Kabupaten Banyumas merupakan kabupaten endemis malaria di Provinsi Jawa Tengah. Data Dinas Kesehatan Kabupaten Banyumas tahun 2008 - 2013 menunjukkan angka annual paracite incidence (API) yang selalu mengalami fluktuasi. Dari 27 kecamatan, 22 di antaranya termasuk dalam kategori medium case incidence (MCI) dan low case incidence (LCI). Faktor lingkungan, perilaku, sosial ekonomi, dan iklim berdampak pada tinggi rendahnya kejadian malaria. Tujuan penelitian adalah mengetahui faktor yang berhubungan dengan API di Kabupaten Banyumas. Data dikumpulkan dari Januari 2011 - Desember 2013 menggunakan penelitian analitik dengan rancangan penelitian potong lintang dan menggunakan data sekunder dari Dinas Kesehatan, Dinas Pertanian, dan Badan Pusat …

Riwayat Pemberian Air Susu Ibu Dengan Penyakit Infeksi Pada Balita, Abidah Nur, Nelly Marissa

Kesmas

Riset Kesehatan Dasar tahun 2013 menyebutkan angka insiden diare pada balita di Indonesia sebesar 6,7%. Aceh merupakan provinsi dengan insiden diare tertinggi, mencapai 10,2%. Profil Kesehatan Aceh menunjukkan bahwa secara umum terjadi peningkatan penyakit infeksi seperti influenza, tuberkulosis, dan diare dalam kurun waktu tujuh tahun (2006 - 2012). Penyakit tersebut dapat dicegah dengan pemberian ASI yang berperan dalam peningkatan kekebalan tubuh. Penelitian ini dilakukan untuk mengetahui hubungan riwayat pemberian ASI dengan penyakit infeksi pada balita. Penelitian ini menggunakan data sekunder dari Badan Pusat Statistik Provinsi Aceh, yaitu data Survei Sosial dan Ekonomi Nasional tahun 2012 dengan jumlah sampel 3.486 balita. …

Analisis Risiko Karakteristik, Sosial Ekonomi, Perilaku Dan Kondisi Lingkungan Rumah Terhadap Kejadian Malaria, Susy Sriwahyuni Sukiswo, Rinidar Rinidar, Sugito Sugito

Kesmas

Malaria merupakan penyakit menular yang menjadi perhatian global. Kecamatan Arongan Lambalek merupakan daerah rawan malaria di Kabupaten Aceh Barat dengan kategori Medium Incidence Area dengan nilai Annual Parasite Incidence (API) 3,67 per 1000 penduduk masih di atas target API Nasional pada fase eliminasi API kurang dari 1 per 1000 penduduk tahun 2013. Penelitian ini bertujuan menganalisis karakteristik, sosial ekonomi, perilaku, dan kondisi lingkungan rumah yang berpengaruh terhadap kejadian malaria di Kecamatan Arongan Lambalek, Kabupaten Aceh Barat. Jenis penelitian ini adalah observasional analitik dengan pendekatan kasus kontrol dengan metode penarikan sampel yaitu purposive sampling. Jumlah sampel dalam penelitian ini terdiri 33 …

Mutu Pelayanan Puskesmas Perawatan Yang Berstatus Badan Layanan Umum Daerah, Putu Ayu Indrayathi, Rina Listyowati, Ni Made Sri Nopiyani, Luh Putu Sinthya Ulandari

Kesmas

Kebijakan pusat pelayanan kesehatan masyarakat (puskesmas) sebagai Badan Layanan Umum Daerah (BLUD) diimplentasikan untuk meningkatkan kualitas pelayanan kesehatan dasar. Kebijakan BLUD puskesmas telah diterapkan di Kabupaten Gianyar sejak tahun 2010 dan berlaku pada puskesmas perawatan maupun nonperawatan. Pelaksanaan BLUD puskesmas tidak selalu meningkatkan mutu layanan. Penelitian ini bertujuan mengetahui gambaran mutu pelayanan puskesmas perawatan yang berstatus BLUD di Kabupaten Gianyar. Penelitian ini merupakan penelitian potong lintang dengan pendekatan kuantitatif dan kualitatif. Tempat dan waktu penelitian ini dilakukan di Kabupaten Gianyar, Agustus hingga Desember 2013. Data kuantitatif dikumpulkan melalui penyebaran kuesioner kepada 105 pengguna layanan di empat puskesmas yang dipilih dengan …