Multilevel modelling of refusal and noncontact nonresponse in household surveys: evidence from six UK government surveys

This paper analyses household unit nonresponse and interviewer effects in six major UK government surveys using a multilevel multinomial modelling approach. The models are guided by current conceptual frameworks and theories of survey participation. One key feature of the analysis is the investigation of survey dependent and independent effects of household and interviewer characteristics, providing an empirical exploration of the leverage-salience theory. The analysis is based on the 2001 UK Census Link Study, a unique data source containing an unusually rich set of auxiliary variables, linking the response outcome of six surveys to census data, interviewer observation data and interviewer information, available for respondents and nonrespondents

Alternative approaches to multilevel modelling of survey noncontact and refusal

We review three alternative approaches to modelling survey noncontact and refusal: multinomial, sequential and sample selection (bivariate probit) models. We then propose a multilevel extension of the sample selection model to allow for both interviewer effects and dependency between noncontact and refusal rates at the household and interviewer level. All methods are applied and compared in an analysis of household nonresponse in the UK, using a dataset with unusually rich information on both respondents and nonrespondents from six major surveys. After controlling for household characteristics, there is little evidence of residual correlation between the unobserved characteristics affecting noncontact and refusal propensities at either the household or the interviewer level. We also find that the estimated coefficients of the multinomial and sequential models are surprisingly similar, which further investigation via a simulation study suggests is due to there being little overlap between the predictors of noncontact and refusal

Mechanical response tissue analyzer for estimating bone strength

One of the major concerns for extended space flight is weakness of the long bones of the legs, composed primarily of cortical bone, that functions to provide mechanical support. The strength of cortical bone is due to its complex structure, described simplistically as cylinders of parallel osteons composed of layers of mineralized collagen. The reduced mechanical stresses during space flight or immobilization of bone on Earth reduces the mineral content, and changes the components of its matrix and structure so that its strength is reduced. Currently, the established clinical measures of bone strength are indirect. The measures are based on determinations of mineral density by means of radiography, photon absorptiometry, and quantitative computer tomography. While the mineral content of bone is essential to its strength, there is growing awareness of the limitations of the measurement as the sole predictor of fracture risk in metabolic bone diseases, especially limitations of the measurement as the sole predictor of fracture risk in metabolic bone diseases, especially osteoporosis. Other experimental methods in clinical trials that more directly evaluate the physical properties of bone, and do not require exposure to radiation, include ultrasound, acoustic emission, and low-frequency mechanical vibration. The last method can be considered a direct measure of the functional capacity of a long bone since it quantifies the mechanical response to a stimulus delivered directly to the bone. A low frequency vibration induces a response (impedance) curve with a minimum at the resonant frequency, that a few investigators use for the evaluation of the bone. An alternative approach, the method under consideration, is to use the response curve as the basis for determination of the bone bending stiffness EI (E is the intrinsic material property and I is the cross-sectional moment of inertia) and mass, fundamental mechanical properties of bone

IV. The Uses of the Indexes of Drilling and Completion Costs

Part 4 of the Monograph in Economics by Henry B. Steel

I. The Need for Adequate Statistical Data Concerning Trends in the Cost of Drilling and Completing Oil and Gas Wells

Part 1 of the Monograph in Economics by Henry B. Steel

V. Limitations on the Use of the Indexes

Part 5 of the Monograph in Economics by Henry B. Steel

Historical Perspectives and New Directions in the Exploitation of Latin American Petroleum Resources

This paper constitutes an attempt, in a very brief compass, to provide an historical survey of the traditional roles of government and private enterprise in the exploitation of Latin American petroleum resources, to evaluate the current situation, and to speculate in a limited manner on the future implications of present developments. The basic analytical frame of reference is that of economics, but since the petroleum industry is a world industry, developments in the Latin American petroleum industry must be placed in the wider context of world oil industry economics and politics. From the standpoint of economic analysis, the major conflict between companies and governments appears to be their divergent goals: the companies strive to minimize costs, while the governments insist upon maximizing the companies\u27 contribution to national treasuries. Expropriation is of course the most dramatic of the recurring themes in Latin American petroleum, and can be understood not only in terms of the vulnerability of foreign private investment to local military force, but also as a matter of economic logic in an extractive industry such as petroleum. In addition, the decision to expropriate may reflect the belief that the nation\u27s oil industry is growing too rapidly. This growth may seem excessive relative to reserves, or it may be feared that unchecked growth over too long a time may produce an industry too large for the state to control. Regardless of intentions, expropriation generally reduces the role of a nation\u27s oil industry in world trade and orients it increasingly toward domestic consumption rather than export specialization

Reproductive Success of the White-Faced Ibis: The Effects of Pesticides and Colony Characteristics

Reproductive success of white-faced ibis (Plegadis chihi) was measured in nine colonies on marshes in northern Utah during 1979. The effects of pesticides and characteristics of colonies and sub-colonies on reproductive success were examined. DDE was present in all 80 eggs sampled and had a geometric mean concentration of 1.25 ppm. Shell thickness of 176 eggs was 4.3 percent below pre-1945 thickness. Shell thickness was weakly correlated with residues of DDT, DDE, Dieldrin, and heptachlor epoxide. Residues of these four pesticides were all correlated with each other. However, because of the stronger correlations between shell thickness and two residues, DDE and DDT, and because of studies in the literature, it was concluded that these two residues were responsible for the observed shell thinning. Observed levels of pesticides did not cause sufficient shell thinning to reduce hatching success, but clutch size was negatively correlated with pesticide residues. Only two characteristics of colonies were observed to be associated with differences in reproductive success. Earlier sub-colonies had larger clutches and larger colonies suffered higher rates of predation. If there are effects of subcolony size, degree of nesting synchrony, vegetation type, or avian species association on reproductive success, they may not be detectable with one year of data