Stopping rules in Bayesian adaptive threshold estimation
Stopping rules in Bayesian adaptive threshold estimation
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DOI：
10.1163/1568568054089375
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发表时间：
2005-01-01
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影响因子：
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通讯作者：
García-Pérez, MA
中科院分区：
文献类型：
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作者：
Alcalá-Quintana, R;García-Pérez, MA
假设所谓的动态停止规则中使用的索引具有诊断价值，用于识别何时获得了准确的估计，那么使用顺序过程进行阈值估计是合理的。本文将五种贝叶斯顺序过程的性能与一种类似的定长过程的性能进行了比较。顺序过程中使用的指标有：(1)贝叶斯概率区间的宽度，(2)后验标准差，(3)绝对变化，(4)平均变化，(5)符号波动的次数。进行了一项模拟研究，以评估哪种指数在是-否和两种选择的强制选择（2AFC）任务中以更低的成本（即更低的平均完成试验次数）以更小的偏差和更小的标准误差给出估计。我们还考虑了心理测量函数的形式和参数的影响，以及它与程序中假设的模型函数的相似性。我们的结果表明，在是-否任务中，顺序过程并不优于固定长度过程。然而，在2AFC任务中，不基于符号波动的顺序程序都比固定长度的程序产生最低限度的更好的估计，尽管大多数改进发生在短期运行中，这会导致不可靠的估计，并且当程序运行一些试验（大约70次）时，差异会消失，从而确保可靠性。因此，这里考虑的指标（其中一些是广泛的）没有一个具有诊断价值，可以证明其使用是合理的。此外，执行的困难使得顺序程序不适合作为固定长度程序的替代品。
Threshold estimation with sequential procedures is justifiable on the surmise that the index used in the so-called dynamic stopping rule has diagnostic value for identifying when an accurate estimate has been obtained. The performance of five types of Bayesian sequential procedure was compared here to that of an analogous fixed-length procedure. Indices for use in sequential procedures were: (1) the width of the Bayesian probability interval, (2) the posterior standard deviation, (3) the absolute change, (4) the average change, and (5) the number of sign fluctuations. A simulation study was carried out to evaluate which index renders estimates with less bias and smaller standard error at lower cost (i.e. lower average number of trials to completion), in both yes-no and two-alternative forced-choice (2AFC) tasks. We also considered the effect of the form and parameters of the psychometric function and its similarity with the model function assumed in the procedure. Our results show that sequential procedures do not outperform fixed-length procedures in yes-no tasks. However, in 2AFC tasks, sequential procedures not based on sign fluctuations all yield minimally better estimates than fixed-length procedures, although most of the improvement occurs with short runs that render undependable estimates and the differences vanish when the procedures run for a number of trials (around 70) that ensures dependability. Thus, none of the indices considered here (some of which are widespread) has the diagnostic value that would justify its use. In addition, difficulties of implementation make sequential procedures unfit as alternatives to fixed-length procedures.