Heckman’s two-step procedure (Heckit) for estimating the parameters in linear models from censored data is frequently used by econometricians, despite of the fact that earlier studies cast doubt on the procedure. In this paper it is shown that estimates of the hazard h for approaching the...

Outbreak detection is of interest for several diseases and syndromes. The aim is to detect the progressing increase in the incidence as soon as possible after the onset of the outbreak. A semiparametric method is applied to Swedish data on tularemia and influenza. The method is constructed to...

In many situations we need a system for detecting changes early. Examples are early detection of disease outbreaks, of patients at risk and of financial instability. In influenza outbreaks, for example, we want to detect an increase in the number of cases. Important indicators might be the...

The aim of sequential surveillance is on-line detection of an important change in an underlying process as soon as possible after the change has occurred. Statistical methods suitable for surveillance differ from hypothesis testing methods. In addition, the criteria for optimality differ from...

In this paper we discuss statistical methods for curve-estimation under the assumption of unimodality for variables with distributions belonging to the two-parameter exponential family with known or constant dispersion parameter. We suggest a non-parametric method based on monotonicity...

Multivariate surveillance is of interest in industrial production as it enables the monitoring of several components. Recently there has been an increased interest also in other areas such as detection of bioterrorism, spatial surveillance and transaction strategies in finance.<p>Several types of...</p>

In financial surveillance the aim is to signal at the optimal trading time. A systematic decision strategy is used. The information available at each possible decision time is evaluated in order to judge whether or not there is enough information for a decision about an action or if more...