Monitoring the parameter changes in general ARIMA time series models

We propose methods for monitoring the residuals of a fitted ARIMA or an autoregressive fractionally integrated moving average (ARFIMA) model in order to detect changes of the parameters in that model. We extend the procedures of Box & Ramirez (1992) and Ramirez (1992) and allow the differencing parameter, d to be fractional or integer. Test statistics are approximated by Wiener processes. We carry out simulations and also apply our method to several real time series. The results show that our method is effective for monitoring all parameters in ARFIMA models.     

Patterns in Cross Shopping for Groceries and their Implications for Co-operation in Retail Location

One determinant of the success of a retail outlet is its location. The location strategies adopted by many retailers of convenience products, including those marketing groceries, have been based upon the principle of siting stores away from competition. Recent moves by leading grocery retailers to develop out of town and other sites jointly, where they would trade side by side, mean that methods are needed to appraise the selection of location partners to supplement or replace traditional, spatial analyses. A method based on similarity of image and cross-shopping behaviour is proposed and tested on two substantial data bases. A concept, drawn from theory on brand switching, that customers would treat outlets seen as similar in a similar way, is found not to apply to source switching. Source switching behaviour is found instead to vary with the source itself, according to two distinct patterns. In one, shoppers cross shop more to retailers perceived to be similar; in the other, shoppers cross shop more to retailers perceived to be different. The strategies currently adopted by four grocery retailers in joint site development are appraised against the model of source switching that can be defined from these patterns. Some location alliances are predicted to be potentially more valuable to one partner than another both in the short and long term. The anomalies identified in the selection of location partners are analysed by reference to concepts drawn from the literature on co-operation. Two different types of relationship exist between the various retail partners; a longer term alliance at each site and shorter co-operation between head offices. It is suggested that the nature of the second could prejudice the outcome of the first.     

Strategic planning for the board

Although the planning operation is regarded by some observers as unrealistic in conditions of rapid change and increasing competition, the discipline of strategic thinking and the need for strategic leadership continue to be of vital importance. The author examines the purpose of the Board of Directors and its role in the management of strategy.     

The changing structure of food retailing in europe: the implications for strategy

European food retailers have increased their scale and scope while concentrating sales into large stores. Strategic implications include the need for scale to compete and organisational relationships to move from supply push to demand pull retailing. Consequences are different for private label and for branded manufacturers, who must respond to the demands of retail supply chains whilst retaining control of product development. Further concentration in both sectors is likely. Consumers are more mobile, but more captive to the retailer in store. Public policy makers are challenged to find new measures of retail power and both allow for innovation and ensure equitable shopping opportunities.