Conditioning as disintegration

Conditional probability distributions seem to have a bad reputation when it comes to rigorous treatment of conditioning. Technical arguments are published as manipulations of Radon–Nikodym derivatives, although we all secretly perform heuristic calculations using elementary definitions of conditional probabilities. In print, measurability and averaging properties substitute for intuitive ideas about random variables behaving like constants given particular conditioning information.
One way to engage in rigorous, guilt-free manipulation of conditional distributions is to treat them as disintegrating measures—families of probability measures concentrating on the level sets of a conditioning statistic. In this paper we present a little theory and a range of examples—from EM algorithms and the Neyman factorization, through Bayes theory and marginalization paradoxes—to suggest that disintegrations have both intuitive appeal and the rigor needed for many problems in mathematical statistics.     

Price rigidities and institutional variations in markets with posted prices

Summary Standard laboratory posted-offer markets respond slowly and incompletely to demand shocks. In these one-sided markets, where sellers control the setting of prices, very little information is transmitted via the process of exchange. For this reason, traders have trouble distinguishing randomness in their own experience from changes in market fundamentals. This paper reports the results of twelve laboratory markets conducted to assess whether some common variants to standard posted-offer rules can correct the adjustment deficiences. Although discounting, multiple postings and excess demand information all improve performance, we find that response remains poor, and efficiencies low.Support for this research was provided by the National Science Foundation (SBR 9319842 and SBR 9320044), and the University of Virginia Bankard Fund. Data are archived at FTP address: fido.econlab.arizona.edu. We wish to thank Charles Plott and Shyam Sunder for useful comments on an earlier draft of this paper. The usual disclaimer applies.     

The Impact of Option Introduction on Stock Return Variances: The Role of Bid-Ask Spreads, Return Autocorrelations, and Intrinsic Variances

The purpose of this paper is to examine changes in stock return variances following option introduction. The sample consists of National Market System stocks and employs both transaction returns and returns based on bid and ask quotes. Variances are decomposed into portions attributable to bid-ask spreads, return autocorrelations, and intrinsic variances. Spreads play a negligible role in explaining variance changes. A generally positive component to short-term autocorrelations falls following option introduction, increasing variances over short holding periods. Intrinsic variances fall prior to the October 1987 crash, but do not change after the crash with option introduction.     

Migration as a Strategy of Accumulation: Social and Economic Change in Eighteenth-Century Savoy

Migration from the mountain areas of pre-industrial Europe has been seen as the product of poverty. While hardship controlled the strategies of the more marginalized households, better placed families used their migration experience to establish themselves in commerce. Over generations they used contacts and kinship systems to develop important informal trading networks. It is difficult to establish the effects of this hidden activity on local mountain economies, but dowry payments and post mortem inventories are used to expose the impact of inflowing capital and its circulation.     

A RE-EXAMINATION OF THE EFFECT OF 12B–1 PLANS ON MUTUAL FUND EXPENSE RATIOS

In this paper we re-examine the effect of 12b–1 payments on mutual fund expense ratios by analyzing data from 1988 through 1991. The findings are consistent with previous studies that find charges are a dead-weight cost borne by shareholders. However, we show that this cost increases over time.     

Nea presidential address, 1991: Sixteenth-century European expansion and the economic decline of Africa (in honor of Walter Rodney)

Prior to the sixteenth century, the Indian Ocean trading network was one of the wealthiest commercial regions in the world. It included states of East Africa, the Arabian peninsula, the Indian subcontinent, Southeast Asia, China and Japan. By circumnavigating Africa, Portugal was the first European nation to gain access to the region. Through the exercise of naval superiority, blockading of strategic shipping lanes, imposition of duties and expulsion of Swahili and Muslim merchants, Portugal exercised a mercantile monopoly which ultimately led to the region’s rapid economic decline. Using rare historical documents from Po rtugal and Africa, this study traces the effects of Portuguese expansion on the economies of East Africa and trade in the Indian Ocean.