国内对函件市场的研究大多是基于经济常识和行业经验的定性分析,但在没有得到实证研究甚至更严格的计量经济学研究的情况下,这些判断严格地说会缺乏一定的科学性和说服力。抽样调查是最为简单的一种说明市场状况的量化分析方法,通过定期的重复调查形成时间序列数据,还可以让我 Domestic research on the letter market is mostly based on the qualitative analysis of economic common sense and industry experience, but these judgments are strictly lacking in certain scientific and persuasive powers without empirical research or even more rigorous econometric research . Sample surveys are the simplest quantitative analysis of how the market is doing. Time series data can be generated from repeated surveys on a regular basis.