Guidelines for samplers: measuring a change in behaviour from before and after surveys
Guidelines for samplers: measuring a change in behaviour from before and after surveys
复制标题
抽样人员指南：衡量调查前后的行为变化
DOI：
10.1007/s11116-006-0002-8
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发表时间：
2007
期刊：
影响因子：
4.3
通讯作者：
S. Greaves
中科院分区：
文献类型：
--
作者：
P. Stopher;S. Greaves
这篇论文讨论了使用前后调查来评估对交通政策和投资做出反应的行为变化的问题，我们认为，这一过程在这个专业中太少做了。此外，它非常清楚地表明，在几乎所有可以想到的情况下，通过使用一个小组(同样，在我们的专业中未得到充分利用)进行评估，而不是连续进行独立的横断面调查，可以获得相当大的经济效益。该文件还讨论了衡量旅行行为中相对较小幅度的变化的样本量要求这一关键问题；即，以95%的置信度说明，如果样本的行为发生∂百分比的变化，则总体行为的∂百分比和±1%的变化，其中e是抽样误差。在这篇文章中，我们提出了一种根据第一原理计算样本大小要求的方法，并使用来自Puget Sound Transport Panel的数据验证了该方法的适用性。该公式使前后调查的设计者能够系统地研究他们预测的统计精度和样本量要求之间的权衡，而不需要事先指定∂。我们认为，后一点是至关重要的，因为我们关于∂的信息有限，然而，正如我们在这里解释的那样，它使用替代的、经常被引用的方法来计算样本量以评估行为变化，从而推动样本量要求。这些结果对那些执行旨在产生行为变化的运输政策的人，特别是当需要对该政策进行成本效益评估时，以及对先前研究报告的结果的解释，都具有重要的影响。
This paper addresses the issue of using before and after surveys to evaluate behavioural changes in response to transport policies and investments, a procedure that, we argue is done far too rarely in this profession. Further, it demonstrates very clearly that, in almost all conceivable cases, there are considerable economies to be obtained by using a panel (again, under-utilised in our profession) to undertake evaluation, rather than successive independent cross-sectional surveys. The paper also addresses the critical issue of sample size requirements for measuring changes of a relatively small magnitude in travel behaviour; i.e., to state, with 95% confidence, that if there is a ∂ percent change in behaviour for the sample, there is a ∂ percent ± e percent change in the behaviour of the population, where e is the sampling error. In this paper, we present a method for calculating such sample size requirements from first principles and demonstrate the applicability both hypothetically and then empirically using data from the Puget Sound Transportation Panel. The formulation enables designers of before and after surveys to investigate the trade-offs between the statistical accuracy of their predictions and the sample size requirements systematically, without the need to specify ∂ a priori. This latter point is crucial, we argue, because we have limited information on ∂, yet, as we explain here, it drives the sample size requirements using alternative, well-cited approaches for calculating sample sizes to assess behavioural change. The results have important ramifications both for those implementing transport policies intended to produce behavioural change, especially when a cost-benefit evaluation of the policy is desired, and for those interpreting the results reported in previous studies.