Directing store flyers to the appropriate audience

Grocery shoppers were questioned about the frequency of purchasing items that were featured in the store's flyers. This measure was used as the dependent variable in a multinomial logit model with the independent variables being various aspects of shopping behaviour, usage of store flyers, age and employment status. Since only one threshold parameter was significant, the four-level dependent variable was then collapsed and a binary model was estimated. This study evidenced that less than half of the respondents looked forward to receiving unsolicited flyers. Most shoppers read the flyers only to be informed of price specials that the store has to offer. The odds ratio of responding to store flyer deals among those who look forward to sales flyers is more than double the odds ratio of those who do not await the flyers, across every category of shopping frequency. Retailers could employ direct marketing to target specific audiences who look forward to receiving store flyers.\u

Most primitive groups are full automorphism groups of edge-transitive hypergraphs

We prove that, for a primitive permutation group G acting on a set of size n, other than the alternating group, the probability that Aut(X,Y^G) = G for a random subset Y of X, tends to 1 as n tends to infinity. So the property of the title holds for all primitive groups except the alternating groups and finitely many others. This answers a question of M. Klin. Moreover, we give an upper bound n^{1/2+\epsilon} for the minimum size of the edges in such a hypergraph. This is essentially best possible.Comment: To appear in special issue of Journal of Algebra in memory of Akos Seres

There's more to volatility than volume

It is widely believed that fluctuations in transaction volume, as reflected in the number of transactions and to a lesser extent their size, are the main cause of clustered volatility. Under this view bursts of rapid or slow price diffusion reflect bursts of frequent or less frequent trading, which cause both clustered volatility and heavy tails in price returns. We investigate this hypothesis using tick by tick data from the New York and London Stock Exchanges and show that only a small fraction of volatility fluctuations are explained in this manner. Clustered volatility is still very strong even if price changes are recorded on intervals in which the total transaction volume or number of transactions is held constant. In addition the distribution of price returns conditioned on volume or transaction frequency being held constant is similar to that in real time, making it clear that neither of these are the principal cause of heavy tails in price returns. We analyze recent results of Ane and Geman (2000) and Gabaix et al. (2003), and discuss the reasons why their conclusions differ from ours. Based on a cross-sectional analysis we show that the long-memory of volatility is dominated by factors other than transaction frequency or total trading volume.Comment: 25 pages, 9 figure

Solid State Physics

Contains reports on two research projects

Entrepreneurship in Africa through the Eyes of GEDI

Since the 1990s, several new indices like the Index of Economic Freedom, Doing Business, Global Competitiveness Index, have been created to achieving real progress in modernizing the business climates of developed and developing countries alike. These indicators however are focused largely on ameliorating burdens for current business, addressing issues with property rights, processes, etc. While necessary conditions, in the public effort to improve the economic incentives and create employment, they remain insufficient to foster the economic font of development: entrepreneurship. It has to be clear that entrepreneurship, and entrepreneurship policy is not merely about small business, or even at times about business at all, but about creating environments where people are able to perceive entrepreneurial opportunities, opportunities to improve their lives and been powered by the environment to act upon their visions. While much has been written about the Global Entrepreneurship Monitor (GEM) and increasingly about the Global Entrepreneurship Development Index (GEDI), this paper represents the first attempt to examine private enterprise development in Africa