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Haybittle–Peto Boundary
The Haybittle–Peto boundary is a rule for deciding when to stop a clinical trial prematurely. It is named for John Haybittle and Richard Peto. The typical clinical trial compares two groups of patients. One group are given a placebo or conventional treatment, while the other group of patients are given the treatment that is being tested. The investigators running the clinical trial will wish to stop the trial early for ethical reasons if the treatment group clearly shows evidence of benefit. In other words, "when early results proved so promising it was no longer fair to keep patients on the older drugs for comparison, without giving them the opportunity to change." The Haybittle–Peto boundary is one such stopping rule, and it states that if an interim analysis shows a probability of equal to, or less than 0.001 that a difference as extreme or more between the treatments is found, given that the null hypothesis is true, then the trial should be stopped early. The final analysi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clinical Trial
Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietary choices, dietary supplements, and medical devices) and known interventions that warrant further study and comparison. Clinical trials generate data on dosage, safety and efficacy. They are conducted only after they have received health authority/ethics committee approval in the country where approval of the therapy is sought. These authorities are responsible for vetting the risk/benefit ratio of the trial—their approval does not mean the therapy is 'safe' or effective, only that the trial may be conducted. Depending on product type and development stage, investigators initially enroll volunteers or patients into small pilot studies, and subsequently conduct progressively larger scale comparative studies. Clinical trials can vary i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Haybittle
Dr John Haybittle (18 October 1922 - 19 November 2017) was a British medical physicist. Haybittle took up a position as junior physicist at Addenbrooke's Hospital in 1948. He worked there until retirement in 1982, by which time he was Chief Physicist. He served as secretary of the British Institute of Radiology from 1962 to 1967, and was editor of the ''British Journal of Radiology'' from 1981 to 1986. He was awarded the British Institute of Radiology's Röntgen Prize in 1972 and their Barclay Medal in 1987. He is a co-inventor, with Richard Peto, of the Haybittle–Peto boundary The Haybittle–Peto boundary is a rule for deciding when to stop a clinical trial prematurely. It is named for John Haybittle and Richard Peto. The typical clinical trial compares two groups of patients. One group are given a placebo or conventio .... References External links * 1922 births Place of birth missing 2017 deaths Medical physicists British radiologists British med ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Peto
Sir Richard Peto (born 14 May 1943) is an English statistician and epidemiologist who is Professor of Medical Statistics and Epidemiology at the University of Oxford, England. Education He attended Taunton's School in Southampton and subsequently studied the Natural Sciences Tripos at Trinity College, Cambridge followed by a Master of Science degree in Statistics at Imperial College London. Career and research His career has included collaborations with Richard Doll beginning at the Medical Research Council Statistical Research Unit in London. He set up the Clinical Trial Service Unit (CTSU) in Oxford in 1975 and is currently co-director. Peto's paradox is named after him. Awards and honours He was elected a Fellow of the Royal Society in 1989 for his contributions to the development of meta-analysis. He is a leading expert on deaths related to tobacco use. "When Sir Richard Peto began work with the late Richard Doll fifty years ago, the UK had the worst death rates from s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placebo
A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures. In general, placebos can affect how patients perceive their condition and encourage the body's chemical processes for relieving pain and a few other symptoms, but have no impact on the disease itself. Improvements that patients experience after being treated with a placebo can also be due to unrelated factors, such as regression to the mean (a statistical effect where an unusually high or low measurement is likely to be followed by a less extreme one). The use of placebos in clinical medicine raises ethical concerns, especially if they are disguised as an active treatment, as this introduces dishonesty into the doctor–patient relationship and bypasses informed consent. While it was once assumed that this deception was necessary for placebos to have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stopping Rule
In probability theory, in particular in the study of stochastic processes, a stopping time (also Markov time, Markov moment, optional stopping time or optional time ) is a specific type of “random time”: a random variable whose value is interpreted as the time at which a given stochastic process exhibits a certain behavior of interest. A stopping time is often defined by a stopping rule, a mechanism for deciding whether to continue or stop a process on the basis of the present position and past events, and which will almost always lead to a decision to stop at some finite time. Stopping times occur in decision theory, and the optional stopping theorem is an important result in this context. Stopping times are also frequently applied in mathematical proofs to “tame the continuum of time”, as Chung put it in his book (1982). Definition Discrete time Let \tau be a random variable, which is defined on the filtered probability space (\Omega, \mathcal F, (\mathcal F_n)_, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P-value
In null-hypothesis significance testing, the ''p''-value is the probability of obtaining test results at least as extreme as the result actually observed, under the assumption that the null hypothesis is correct. A very small ''p''-value means that such an extreme observed outcome would be very unlikely under the null hypothesis. Reporting ''p''-values of statistical tests is common practice in academic publications of many quantitative fields. Since the precise meaning of ''p''-value is hard to grasp, misuse is widespread and has been a major topic in metascience. Basic concepts In statistics, every conjecture concerning the unknown probability distribution of a collection of random variables representing the observed data X in some study is called a ''statistical hypothesis''. If we state one hypothesis only and the aim of the statistical test is to see whether this hypothesis is tenable, but not to investigate other specific hypotheses, then such a test is called a null ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pocock Boundary
The Pocock boundary is a method for determining whether to stop a clinical trial prematurely. The typical clinical trial compares two groups of patients. One group are given a placebo or conventional treatment, while the other group of patients are given the treatment that is being tested. The investigators running the clinical trial will wish to stop the trial early for ethical reasons if the treatment group clearly shows evidence of benefit. In other words, "when early results proved so promising it was no longer fair to keep patients on the older drugs for comparison, without giving them the opportunity to change." The concept was introduced by the medical statistician Stuart Pocock in 1977. The many reasons underlying when to stop a clinical trial for benefit were discussed in his editorial from 2005. Details The Pocock boundary gives a ''p''-value threshold for each interim analysis which guides the data monitoring committee on whether to stop the trial. The boundary used d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clinical Research
Clinical research is a branch of healthcare science that determines the safety and effectiveness ( efficacy) of medications, devices, diagnostic products and treatment regimens intended for human use. These may be used for prevention, treatment, diagnosis or for relieving symptoms of a disease. Clinical research is different from clinical practice. In clinical practice established treatments are used, while in clinical research evidence is collected to establish a treatment. Overview The term "clinical research" refers to the entire bibliography of a drug/device/biologic, in fact any test article from its inception in the lab to its introduction to the consumer market and beyond. Once the promising candidate or the molecule is identified in the lab, it is subjected to pre-clinical studies or animal studies where different aspects of the test article (including its safety toxicity if applicable and efficacy, if possible at this early stage) are studied. In the United States ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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