the RES conference, and the 6th ECB Workshop on Forecasting Techniques for comments at various versions of this paper. We also thank Constantinos Kourouyiannis, Michael Sockin, Athanasia Petsa, and Elena Pilavaki for providing excellent research assistance on various parts of the paper.

a b s t r a c tWe study regression models that involve data sampled at different frequencies. We derive the asymptotic properties of the NLS estimators of such regression models and compare them with the LS estimators of a traditional model that involves aggregating or equally weighting data to estimate a model at the same sampling frequency. In addition we propose new tests to examine the null hypothesis of equal weights in aggregating time series in a regression model. We explore the above theoretical aspects and verify them via an extensive Monte Carlo simulation study and an empirical application.

CIRANOLe CIRANO est un organisme sans but lucratif constitué en vertu de la Loi des compagnies du Québec. Reproduction partielle permise avec citation du document source, incluant la notice ©. Short sections may be quoted without explicit permission, provided that full credit, including © notice, is given to the source. ISSN 1198-8177Ce document est publié dans l'intention de rendre accessibles les résultats préliminaires de la recherche effectuée au CIRANO, afin de susciter des échanges et des suggestions. Résumé / AbstractNous proposons des extensions de la théorie asymptotique de Foster et Nelson pour l'estimation de variance. Nous proposons une approximation asymptotique qui permet de comparer des estimateurs obtenus à partir de données avec fréquences d'échantillonnage différentes. Une autre extension consiste à appliquer les arguments de Foster et Nelson à des processus plus généraux tels que la volatilité intégrée. Foster and Nelson (1996) We would like to thank Tim Bollerslev and Denise Osborn for comments on an earlier draft of this paper. We would also like to thank Michel Dacorogna of Olsen and Associates for providing us the data. We propose different extensions of the continuous record asymptotic analysis for rolling sample variance estimators developed by

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SUMMARYThe paper evaluates the performance of several recently proposed tests for structural breaks in the conditional variance dynamics of asset returns. The tests apply to the class of ARCH and SV type processes as well as data-driven volatility estimators using high-frequency data. In addition to testing for the presence of breaks, the statistics identify the number and location of multiple breaks. We study the size and power of the new tests for detecting breaks in the conditional variance under various realistic univariate heteroscedastic models, change-point hypotheses and sampling schemes. The paper concludes with an empirical analysis using data from the stock and FX markets for which we find multiple breaks associated with the Asian and Russian financial crises. These events resulted in changes in the dynamics of volatility of asset returns in the samples prior and post the breaks.

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Background: The aim of this review is to identify the roles and activities of nurses working with people with diabetes and to examine the facilitators and barriers in caring for such people. Methods: A systematic review was conducted. From 531 abstracts reviewed, 29 studies were included (18 studies comprised questionnaire surveys, one was an intervention study, two used both questionnaires and interviews, and eight of them used interviews). Barriers and facilitators were extracted and combined using qualitative synthesis. Results: The literature review revealed three major roles and a number of barriers. A model for achieving enhanced nursing care of patients with diabetes has been developed according to the findings of this literature. Specifically, a stepladder suggesting that through better nursing training and education and by providing adequate resources, time, and synergies to diabetes specialists, nurses will be able to correctly perform their diabetes care roles, which include patient education, advanced care, and psychological support. Conclusions: Taking into serious consideration that a large number of hospital users are people with diabetes and that there is an inconsistency among countries about the work settings of Diabetes Specialist Nurses (DSNs), it is important to give greater focus to inpatient care and perhaps to enhance nurses’ roles by eliminating any barriers that prevent them from providing adequate quality care. Furthermore, integrated care involving the role of DSNs within the inpatient care would have been more beneficial for patients.

This article, which presents a regression framework that relates the quarterly macro variable (such as GDP growth) to higher-frequency variables in a relatively simple, parsimonious way, is organized as follows. Section 2 covers mixed data sampling (MIDAS) regressions. Section 3 covers so-called nowcasting, and the Kalman filter and its relationship with MIDAS regressions. The final section discusses volatility models using mixed frequencies.