Guidelines for estimating repeatability
Guidelines for estimating repeatability
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DOI：
10.1111/j.2041-210x.2011.00125.x
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发表时间：
2012-02-01
影响因子：
6.6
通讯作者：
Paulsen, Yale R.
中科院分区：
文献类型：
--
作者：
Wolak, Matthew E.;Fairbairn, Daphne J.;Paulsen, Yale R.
1.研究人员经常对样本中的个体进行重复测量，目的是量化可归因于个体之间的变异与个体内测量值之间的变异的总变异的比例。归因于个体间变异的变异比例被称为重复性，最常被估计为组内相关系数（ICC）。我们研究的目的是提供确定准确估计ICC所需的样本量（个体数量和每个个体的测量数量）的指南。我们从文献中报告了一系列ICC，并估计这些估计值的95%置信区间。我们引入了Bonett（2002）推导的预测方程，并通过模拟测试了该方程的假设。最后，我们创建了一个R统计包来规划实验和估计ICC。3.重复性估计报告在15%的文章发表在接受调查的期刊。重复性往往是最高的ICC时，用于估计测量误差和最低时，它被用来估计重复性的行为和生理性状。很少有作者报告置信区间，但我们对已发表ICC的95%置信区间估计通常表明与这些估计相关的精度水平较低。这项调查表明，需要一个协议，以估计可重复性。从Bonett方程在一系列的样本量，预期的重复性和所需的置信区间宽度的预测分析产生的分析和直观的指导方针，设计实验，以估计重复性。然而，我们发现当ICC高时，置信区间被方程低估，而当ICC和每个个体的测量次数低时，置信区间被高估。估计重复性时使用的样本量是一个问题，使研究者的努力与估计的预期精度相矛盾。我们提供的指南适用于各种生态和进化研究，估计可重复性，测量误差或遗传性。此外，我们还提供了R软件包icc，以便于在计划实验以估计可重复性时进行分析并确定最经济的资源使用。
1. Researchers frequently take repeated measurements of individuals in a sample with the goal of quantifying the proportion of the total variation that can be attributed to variation among individuals vs. variation among measurements within individuals. The proportion of the variation attributed to variation among individuals is known as repeatability and is most frequently estimated as the intraclass correlation coefficient (ICC). The goal of our study is to provide guidelines for determining the sample size (number of individuals and number of measurements per individual) required to accurately estimate the ICC.2. We report a range of ICCs from the literature and estimate 95% confidence intervals for these estimates. We introduce a predictive equation derived by Bonett (2002), and we test the assumptions of this equation through simulation. Finally, we create an R statistical package for the planning of experiments and estimation of ICCs.3. Repeatability estimates were reported in 1 5% of the articles published in the journals surveyed. Repeatabilities tended to be highest when the ICC was used to estimate measurement error and lowest when it was used to estimate repeatability of behavioural and physiological traits. Few authors report confidence intervals, but our estimated 95% confidence intervals for published ICCs generally indicated a low level of precision associated with these estimates. This survey demonstrates the need for a protocol to estimate repeatability.4. Analysis of the predictions from Bonett's equation over a range of sample sizes, expected repeatabilities and desired confidence interval widths yields both analytical and intuitive guidelines for designing experiments to estimate repeatability. However, we find a tendency for the confidence interval to be underestimated by the equation when ICCs are high and overestimated when ICCs and the number of measurements per individual are low.5. The sample size to use when estimating repeatability is a question pitting investigator effort against expected precision of the estimate. We offer guidelines that apply over a wide variety of ecological and evolutionary studies estimating repeatability, measurement error or heritability. Additionally, we provide the R package, icc, to facilitate analyses and determine the most economic use of resources when planning experiments to estimate repeatability.