This paper proposes a family of estimators of population mean using information on several auxiliary variables and analyzes its properties in the presence of measurement errors.

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Each individual investor is different, with different financial goals, different levels of risk tolerance and different personal preferences. From the point of view of investment management, these characteristics are often defined as objectives and constraints.Objectives can be the type of return being sought, while constraints include factors such as time horizon, how liquid the investor is, any personal tax situation and how risk is handled. It's really a balancing act between risk and return with each investor having unique requirements, as well as a unique financial outlook -essentially a constrained utility maximization objective. To analyze how well a customer fits into a particular investor class, one investment house has even designed a structured questionnaire with about two-dozen questions that each has to be answered with values from 1 to 5. The questions range from personal background (age, marital state, number of children, job type, education type, etc.) to what the customer expects from an investment (capital protection, tax shelter, liquid assets, etc.). A fuzzy logic system has been designed for the

A gradient algorithm is defined which adaptively minimizes the energy output of a finite impulse response digital filter, for an arbitrary input, by varying the filter coefficients. For a stationary input signal this is equivalent to solving the linear estimation equations for an all-pole system model. The algorithm is simple and is probably easier to implement than the matrix equation methods required by direct solutions of the linear equations. Moreover, real-time hardware using this general approach is already available in data transmission equalizers and echo cancellers. We describe a realization of the algorithm using a small computer and real-time digital filter hardware. We also discuss investigations of the performance of this system in real-time tracking of nonstationary signal sources and in extracting time-varying human vocal-tract resonances.

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