منابع مشابه
Type I and II error
Type I error A type I error occurs when one rejects the null hypothesis when it is true. The probability of a type I error is the level of significance of the test of hypothesis, and is denoted by *alpha*. Usually a one-tailed test of hypothesis is is used when one talks about type I error. Examples: If the cholesterol level of healthy men is normally distributed with a mean of 180 and a standa...
متن کاملEvaluation of Clinical Trials
In a number of important clinical issues such as evaluation of the efficacy or effectiveness of therapeutic or preventive interventions as well as for comparing the harms of interventions, randomized controlled trials (RCTs) provide the highest levels of evidence, either directly or indirectly. It is obvious that critical appraisal of these studies to assess their validity and precision is of p...
متن کاملModeling Heterogeneity in Phase II Clinical Trials
Problem statement: The common assumption in non-randomized Phase II clinical trials is a homogeneous population with homogeneous response. This assumption is at odds with many trials today; a heterogeneous response due to the existence of subgroups. Approach: In order to examine the effects of heterogeneity on the trial outcome, a systematic platform is developed to quantify the range and class...
متن کاملMaximum type 1 error rate inflation in multiarmed clinical trials with adaptive interim sample size modifications
Sample size modifications in the interim analyses of an adaptive design can inflate the type 1 error rate, if test statistics and critical boundaries are used in the final analysis as if no modification had been made. While this is already true for designs with an overall change of the sample size in a balanced treatment-control comparison, the inflation can be much larger if in addition a modi...
متن کاملEvidence Based Medicine: Clinical Trials
Evidence based medicine is very important for success of modern medicine. It is the ongoing process of using the most reliable evidence from clinical studies, scientific understanding and medical practice to make the best possible medical choice for patients. Evidence based medicine is how medicine advances and how we get improvements in life expectancy and quality of life. It not only identifi...
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ژورنال
عنوان ژورنال: Gastroenterology
سال: 1980
ISSN: 0016-5085
DOI: 10.1016/0016-5085(80)90113-4