BACKGROUND To stop a possible outbreak of Legionnaires' disease (LD) at an early stage an outbreak detection programme was installed in The Netherlands. METHODS The programme consisted of sampling and controlling of potential sources to which LD patients had been exposed during their incubation period. Potential sources were considered to be true sources of infection if two or more LD patient...

The data used in social, behavioural, health or biological sciences may have a hierarchical structure due to the natural structure in the population of interest or due to the sampling design. Multilevel or marginal models are often used to analyse such hierarchical data. The data may include sample units selected with unequal probabilities from a clustered and stratified population. Inferences ...

Mobility load balancing (MLB) redistributes the traffic load across the networks to improve the spectrum utilisation. This paper proposes a self-organising cluster-based cooperative load balancing scheme to overcome the problems faced by MLB. The proposed scheme is composed of a cell clustering stage and a cooperative traffic shifting stage. In the cell clustering stage, a user-vote model is pr...

PAUL ALAN FLYER. Finite Population Correction for Replication Estimates of Variance. (Under the direction of CHIRAYATH M. SUCHINDRAN and LESTER R. CURTIN.) For large, national surveys, stratified two stage sample designs are frequently used. In these surveys, unequal probability sampling is almost always used in the selection of first stage units. Typically, the sampling procedure does not allo...

This paper deals with estimation of probabilities of rare events in static simulation models using a fast adaptive two-stage procedure based on importance sampling and Kullback-Liebler’s cross-entropy (CE). More specifically, at the first stage we estimate the optimal parameter vector in the importance sampling distribution using CE, and at the second stage we estimate the desired rare event pr...

Nationally representative samples of large populations often have complex design features for a variety of reasons (e.g., cost efficiency). For purposes of estimating sampling variances based on complex multi-stage sample designs involving stratification and cluster sampling, the sampling error codes provided by survey organizations in public use survey data files often assume “ultimate cluster...

Designing an efficient sampling scheme for a rare and clustered population is a challenging area of research. Adaptive cluster sampling, which has been shown to be viable for such a population, is based on sampling a neighborhood of units around a unit that meets a specified condition. However, the edge units produced by sampling neighborhoods have proven to limit the efficiency and applicabili...

evidence provided from studies in iran points to a possible bias in application of the standard epi cluster sampling procedure, when carried out in populations with highly variant birth rates, tends to over-represent the low birth rate, i.e. higher socio-economic, strata, and if the entity under study shows significant socio-economic gradient, then the estimates arrived at by this method might ...

We compared 2 sampling strategies designed to estimate abundance of double-crested cormorants (Phalacrocorax auritus, hereafter cormorants) on aquaculture ponds in western Mississippi. Cormorants are a major predator of cultured channel catfi sh (Ictalurus punctatus) in this region; thus, estimating cormorant abundance is needed to better determine their economic impact. We independently design...

When an experiment is conducted, such as tossing coins, rolling a die, sampling for estimating the proportion of defective units, several outcomes or events occur with certain probabilities. These events or outcomes may be regarded as a variable which takes different values and each value is associated with a probability. The values of this variable depends on chance or probability. Such a vari...