Human-based surveys such as medical and social science are often characterized by non-response or missing observations. In this study, a new class of regression-type mean imputation method that uses X̄n an estimate X̄ was suggested. Using partial derivative approach, the MSEs estimators presented were derived up to first order approximation under two cases. Case I: when secondary sample S2 size n...

A sample is a group of objects or readings taken from a population for counting or measurement. We shall distinguish between two kinds of populations — finite populations and infinite populations. The sample must be random, meaning that all possible samples of a particular size must have equal probabilities of being chosen from the population. This will prevent bias in the sampling process. Mos...

We present a new type of optical wave-front sensor: the sampling field sensor (SFS). The SFS attempts to solve the problem of real-time optical phase detection. It has a high space-bandwidth product and can be made compact and vibration insensitive. We describe a particular implementation of this sensor and compare it, through numerical simulations, with a more mature technique based on the Sha...