Within
Normal Limits
of
Reason

"Chance is the very guide of life"

"In practical medicine the facts are far too few for them to enter into the calculus of probabilities... in applied medicine we are always concerned with the individual" -- S. D. Poisson

October 22, 2005

Bootstrap analysis of multivariate failure time data.

Bootstrap analysis of multivariate failure time data.: " Bootstrap analysis of multivariate failure time data. Stat Med. 2005 Oct 19;24(22):3387-3400 Authors: Monaco J, Cai J, Grizzle J Multivariate failure time data often arise in research. Cox proportional hazards modelling is a widely used method of analysing failure time data for independent observations. However, when failure times are correlated the Cox proportional hazards model does not yield valid estimates of standard errors or significance tests. Many methods for the analysis of multivariate failure time data have been proposed. These methods commonly test hypotheses about the regression parameters, a practice which averages the treatment effect across time. The purpose of this paper is to examine the bootstrap method for obtaining standard errors in the multivariate failure time case, particularly when the focus is the survival probability or the treatment effect at a single time point such as in a surgical trial. Our motivating example comes from the Asymptomatic Carotid and Atherosclerosis Study (ACAS) in which the outcome of stroke or perioperative complications could be observed for either or both carotid arteries within each patient. Extensive simulation studies were conducted to examine the bootstrap procedure for analysing correlated failure time data under a variety of conditions incl"

1 comment:

bubbalop said...

Napa, CA (PRWEB) February 3, 2006 -- California Peptide Research, Inc. (www.californiapeptide.com), a peptide synthesis company located in Napa, California, announced today that they have synthetic obestatin available for bio medical research. Obestatin is a new discovery in the search of a real treatment for obesity, and shows great promise.

The beautiful Napa Valley, a place that most folks associate with fine wines, beautiful scenery and bed and breakfasts is also a place that produces peptides for research. Among the many peptides produced there, is one that is a recent discovery and may help millions that want to lose weight.

The peptide is called obestatin and it was discovered by researchers at the Stanford University School of Medicine. It is one of many appetite-regulating hormones found in several mammals, including humans and may be the key to an actual treatment for obesity.

Obestatin is a sibling hormone to the hunger hormone known as ghrelin, which is an appetite-booster made in the stomach. However, scientists are calling obestatin the "anti-ghrelin" because it works exactly the opposite of ghrelin.

Early tests of the effects of obestatin in rats shows great promise. Rats injected with obestatin ate less and lost weight. More research needs to be done, of course in the months and years ahead to ensure it does in humans what it apparently is doing for the lab rats.

More information for researchers can be found on California Peptide Research, Inc.'s website www.californiapeptide.com.

California Peptide Research, Inc. offers a wide variety of peptides including Obestatin, Adrenomedullins, Endothelins, Endothelin Antagonists, Enzyme Substrates and Inhibitors, Sulfated Peptides such as CCK and Caerulien, and a great number of Beta Amyloids which have been found to offer useful tools in Alzheimer's research.