Comparison of techniques for estimating the frequency selectivity of bandlimited channels

A transmission channel used in application such as telecommunications can be modeled as a bandpass filter. Measurement of the frequency selectivity of the channel is important to ensure that the information-bearing signal has minimal distortion and loss of information. A comparison is made for several methods used for estimating the frequency selectivity of the transmission. The methods presented are the correlation method, instantaneous energy and frequency estimation and the cross Wigner-Ville distribution. The theoretical foundations and assumptions are described for each method. In general, all the methods gave similar performance in terms of the frequency selectivity. Due to the shorter analysis duration, both the instantaneous energy and frequency estimation and cross Wigner-Ville distribution is ideal for estimating the frequency selectivity of time-varying channel

Interactions of age-dependent mortality and selectivity functions in age-based stock assessment models

The natural mortality rate (M) of fish varies with size and age, although it is often assumed to be constant in stock assessments. Misspecification of M may bias important assessment quantities. We simulated fishery data, using an age-based population model, and then conducted stock assessments on the simulated data. Results were compared to known values. Misspecification of M had a negligible effect on the estimation of relative stock depletion; however, misspecification of M had a large effect on the estimation of parameters describing the stock recruitment relationship, age-specific selectivity, and catchability. If high M occurs in juvenile and old fish, but is misspecified in the assessment model, virgin biomass and catchability are often poorly estimated. In addition, stock recruitment relationships are often very difficult to estimate, and steepness values are commonly estimated at the upper bound (1.0) and overfishing limits tend to be biased low. Natural mortality can be estimated in assessment models if M is constant across ages or if selectivity is asymptotic. However if M is higher in old fish and selectivity is dome-shaped, M and the selectivity cannot both be adequately estimated because of strong interactions between M and selectivity

Time Use Dynamics in Paid Work and Household Activities of Married Women - A Panel Analysis with Household Information and Regional Labour Demand

The dynamics of multiple time use in paid work and in household activities with housework, child rearing and DIY of married women are analyzed with a two step procedure: the estimation of the participation decision in intertemporal labor force participation strategies (entering, leaving the labor market, permanently employed and not employed) by a multinomial logit approach is followed by a selectivity bias corrected simultaneous hours equations systems (C3SLS) estimation of the determinants of hours supplied in multiple time use activities. Microdata base is the German Socio-Economic Panel with four waves (1984-1987), where information of the household - including the husband's employment situation - is merged with regional economic and local labour demand indicators.Dynamics of multiple time use, market and non-market activities, female labour supply, multiple longitudinal labor and activity supply of married women, panel analysis with regional information, selectivity bias corrected simultaneous equations system estimation of multiple time use

Time Use Dynamics in Paid Work and Household Activities of Married Women - A Panel Analysis with Household Information and Regional Labour Demand

The dynamics of multiple time use in paid work and in household activities with housework, child rearing and DIY of married women are analyzed with a two step procedure: the estimation of the participation decision in intertemporal labor force participation strategies (entering, leaving the labor market, permanently employed and not employed) by a multinomial logit approach is followed by a selectivity bias corrected simultaneous hours equations systems (C3SLS) estimation of the determinants of hours supplied in multiple time use activities. Microdata base is the German Socio-Economic Panel with four waves (1984-1987), where information of the household - including the husband's employment situation - is merged with regional economic and local labour demand indicators.Dynamics of multiple time use, market and non-market activities, female labour supply, multiple longitudinal labor and activity supply of married women, panel analysis with regional information, selectivity bias corrected simultaneous equations system estimation of multiple time use

Variation of migration behaviour in population

This paper examines the impact of work status and wages on interregional migration decisions in Finland. Although several studies have controlled for migrant selectivity in the estimation of wages, hardly any have considered the role of work status in the same context. The purpose of this paper is to control for them both in the estimation of selectivity corrected wage equations. In addition, we use the corrected wage predictions as additional determinants when we model the decision of work status. The data is derived from a one-percent random sample from the Finnish Longitudinal Census File. The empirical analysis mainly utilises data from the years 1994 and 1995. The data include information on personal and family status, past labour market record, and regional characteristics of over 60,000 persons. A classification into growth-centre regions and peripheral regions is exploited in the analysis.

On Production Function Estimation with Selectivity and Risk Considerations

In the estimation of production functions, ignoring risk considerations can cause inefficient estimates, while biased parameter estimates arise in the presence of sample selection. In the presence of uncertainty and selection bias, the latter introduced by the endogeneity of qualitative characteristics of inputs in crop choice, we show that correcting for risk considerations (a la Just and Pope, 1978, 1979) but not selection bias, can produce incorrect inferences in terms of risk behavior. The arguments raised in this study have estimation and policy implications for stochastic production analysis applied to all goods whose qualitative characteristics can affect sample selection.crop choice, production risk, sample selection, Production Economics,