Efficiency with costly information: a reinterpretation of evidence from managed portfolios

We investigate the informational efficiency of mutual fund performancefor the period 1965-84. Results are shown to be sensitive tothe measurement of performance chosen. We find that returnson S&P stocks, returns on non-S&P stocks, and returnson bonds are significant factors in performance assessment.Once we correct for the impact of non-S&P assets on mutualfund returns, we find that mutual funds do not earn returnsthat justify their information acquisition costs. This is consistentwith results for prior periods.     

Survivor bias and mutual fund performance

Mutual fund attrition can create problems for a researcher becausefunds that disappear tend to do so due to poor performance.In this article we estimate the size of the bias by trackingall funds that existed at the end of 1976. When a fund mergeswe calculate the return, taking into account the merger terms.This allows a precise estimate of survivorship bias. In addition,we examine characteristics of both mutual funds that mergerand their partner funds. Estimates of survivorship bias overdifferent horizons and using different models to evaluate performanceare provided.     

铜版纸胶印油墨组分的可视化分析

近年来,人们在纸张吸墨性与印品密度的关系方面进行了广泛的研究。本文将一系列热固型油墨的各组分分别印刷到铜版纸上,利用聚焦离子束（FIB）观察各组分的分布情况。然后利用同样的方法,观察成品油墨印刷时各组分的分布情况。油墨光油也适用于改良的薄层色谱（TLC）板,这些薄板与纸张涂有相同的涂层。TLC板上分离的油墨组分可以使用红外光谱来测定。实验结果表明,聚焦离子束可对进入涂料层的油墨组分进行观察,但是矿物油例外。由于其具有挥发性,在干燥后和真空环境内不能留在纸张涂层内,同时注意到当蜡溶解在油里的样品同样要求在涂层的孔隙结构有一个非常清晰的成像时,FIB图像的差异显著增加。这项研究与其他已知研究结果一致,即颜料和硬树脂留在涂层的表面,而矿物油和植物油迅速渗透进入涂层。酯类溶剂和溶解蜡同样渗入涂层。