随机试验中的样本大小计算:强制性和神秘性
Kenneth F Schulz1, David A Grimes
1Family Health International, PO Box 13950, Research Triangle Park, NC 27709, USA. KSchulz@fhi.org
Lancet (London, England)
|April 13, 2005
概括
准确的样本大小计算对于随机试验至关重要. 然而,在功能不足的试验中,方法严谨和透明的报告仍然可以产生有价值的,公正的结果,优先考虑质量而不是精确的数字.
科学领域:
- 临床试验方法论 临床试验方法论
- 生物统计学 生物统计学
- 研究伦理学研究伦理学
背景情况:
- 样本大小计算是随机试验的标准先决条件,影响其感知到的伦理地位.
- 在这些计算中确定效果大小涉及主观的临床判断,这显著影响所需的样本大小.
- 当前的做法往往导致试验被标记为不道德的基于在样本大小的确定感知不准确性.
研究的目的:
- 质疑随机试验由于样本大小计算不准确而被标记为不道德的伦理含义.
- 倡导将重点从样本大小固定转移到研究方法质量的重要性.
- 强调公正的试验的价值,即使有不准确的结果,也不会有任何结果.
主要方法:
- 该研究批判性地检查了随机试验中先验样本大小计算的过程和影响.
- 它分析了主观临床判断对效果大小确定及其随后对样本大小的影响.
- 作者提出了对评估研究研究的伦理地位和价值的替代观点.
主要成果:
- 不准确的样本大小计算不应该自动使试验不道德.
- 缺乏实力的试验可以在道德上被接受,并且在科学上有价值,如果它们采用严格的方法来最大限度地减少偏见.
- 优先考虑方法严谨性和透明报告是比固定精确的样本大小更有利的.
结论:
- 建议在随机试验中更重视方法质量和消除偏见.
- 公正的试验结果,即使不准确,也比不存在数据更可取.
- 临床医生和患者从可靠的,公正的研究结果中受益,而不管确切的样本大小精度如何.
相关概念视频
02:01Group Design
The most basic experimental design involves two groups: the experimental group and the control group. The two groups are designed to be the same except for one difference— experimental manipulation. The experimental group gets the experimental manipulation—that is, the treatment or variable being tested—and the control group does not. Since experimental manipulation is the only difference between the experimental and control groups, we can be sure that any differences between the two are due to...
01:09Random Sampling Method
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01:09Random Variables
A random variable is a single numerical value that indicates the outcome of a procedure. The concept of random variables is fundamental to the probability theory and was introduced by a Russian mathematician, Pafnuty Chebyshev, in the mid-nineteenth century.
Uppercase letters such as X or Y denote a random variable. Lowercase letters like x or y denote the value of a random variable. If X is a random variable, then X is written in words, and x is given as a number.
For example, let X = the...
Uppercase letters such as X or Y denote a random variable. Lowercase letters like x or y denote the value of a random variable. If X is a random variable, then X is written in words, and x is given as a number.
For example, let X = the...
01:19Sample Size Calculation
Knowledge of the sample size is the first requirement to conduct random sampling or an experiment. The sample size is the total number of units, observations, or groups (in some cases) used to get the data to estimate a population parameter. As the name suggests, the sample size is that of the sample drawn from the population and differs from the population size.
The sample size for the given experiment or sampling effort is fundamental to any study design. Sample size decides the number of...
The sample size for the given experiment or sampling effort is fundamental to any study design. Sample size decides the number of...
01:13Randomized Experiments
The randomization process involves assigning study participants randomly to experimental or control groups based on their probability of being equally assigned. Randomization is meant to eliminate selection bias and balance known and unknown confounding factors so that the control group is similar to the treatment group as much as possible. A computer program and a random number generator can be used to assign participants to groups in a way that minimizes bias.
Simple randomization
Simple...
Simple randomization
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01:17Wald-Wolfowitz Runs Test II
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For binary data, runs are identified using symbols such as + and −, or equivalently, 1s and 0s. In...
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