Reporting of observational studies is often inadequate, hampering the assessment of their strengths and weaknesses and, consequently, the generalization of study results. The initiative named Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) developed a checklist of 22 items, the STROBE Statement, with recommendations about what should be included in a more accurate ...

After some general comments about observational studies and experiments, three examples of observational studies and their graphical representation are outlined. A distinction between direct and indirect distortion of effects by unobserved variables is drawn. Indirect distortion is illustrated by an example on bladder cancer.

BACKGROUND Previous studies have assessed the validity of the observational study design by comparing results of studies using this design to results from randomized controlled trials. The present study examined design features of observational studies that could have influenced these comparisons. METHODS To find at least 4 observational studies that evaluated the same treatment, we reviewed ...

OBSERVATIONAL STUDIES OF SOFTWARE ENGINEERING USING DATA FROM SOFTWARE REPOSITORIES Daniel Pierce Delorey Department of Computer Science Master of Science Data for empirical studies of software engineering can be difficult to obtain. Extrapolations from small controlled experiments to large development environments are tenuous and observation tends to change the behavior of the subjects. In thi...

background since the discovery of helicobacter pylori, several clinical reports have demonstrated that h. pylori infection has emerged as a new cause of refractory iron stores in children. we carried out a systematic literature review to primarily evaluate the existing evidence on the association between childhood h. pylori infection and iron deficiency anemia (ida) and secondly, to investigate...

Claims based on observational studies that a treatment has certain effects are often met with counterclaims asserting that the treatment is entirely without effect, that all associations with treatment are produced by biased treatment assignment. Some counterclaims undermine themselves in the following specific sense: presuming the counterclaim to be true may strengthen the support that the ori...

This paper investigates the use of Design of Experiments in observational studies in order to select informative observations and features for classification. D-optimal plans are searched for in existing data and based on these plans the variables most relevant for classification are determined. The adapted models are then compared with respect to their predictive accuracy on an independent tes...

Randomized controlled trials of therapies for the primary and secondary prevention of cardiovascular disease increasingly are powered to study overall mortality. The interventions frequently treat asymptomatic risk factors among high-risk patients and have a diverse spectrum of potential adverse effects. Thus, medications such as clofibrate or encainide that successfully alter surrogate end poi...

We present a theory of environmental bisimilarity for the delimited-control operators shift and reset. We consider two different notions of contextual equivalence: one that does not require the presence of a top-level control delimiter when executing tested terms, and another one, fully compatible with the original CPS semantics of shift and reset, that does. For each of them, we develop sound ...