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

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

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

Selection of Foraging and Nesting Sites by Black-Throated Blue Warblers: Their Relative Influence on Habitat Choice

To understand why breeding Black-throated Blue Warblers (Dendroica caerulescens) select forests with dense shrubs, I assessed the value of this habitat in supplying opportunities for foraging and nesting. I predicted that these warblers would select shrub foliage for foraging if foraging substrate was important in their selection of habitat and that they would place their nests in areas of dense shrubs if nest-site availability affected habitat choice. To measure foraging and nest-site selection, I compared the proportion of foraging or nests in a particular habitat element to the availability of that element expressed as a proportion of all habitat elements. Foraging males under-utilized shrub foliage (below 3 m) in relation to its relative availability and over-utilized the sparse foliage between 3-9 m high. On a horizontal plane, males over-utilized areas of their territories with dense shrub foliage, but this could be due to the greater number of shrubs in these areas. Small samples of females and males feeding fledglings indicated that the lower foliage strata, but not necessarily dense shrub patches, might be important to these groups. These results demonstrate differences in foraging patterns between the sexes and between stages of the breeding cycle. More importantly, foraging Black-throated Blue Warblers showed no consistent selection of dense shrubs. As this species is more abundant in forests with dense shrubs, these analyses suggest that foraging may have a minor influence on habitat selection. Black-throated Blue Warblers consistently selected areas of dense shrubs for nesting. Number of shrub stems and amount of foliage (0-1 m high) were significantly higher at nests than at random points. Furthermore, on an experimental plot with chemically defoliated shrubs, males continued to forage, but nesting was markedly reduced. These results suggest that, while shrubs are used for both foraging and nesting, nest-site requirements may be more important in determining what habitat is selected by Black-throated Blue Warblers. If nest-site requirements determine habitat choices in other forest birds, then the availability of suitable nest-sites should have an important effect on community structure