Univariate analyses were performed to examine the covariates age, sex, room-mates' smoking habits, job title, time spent outdoors, transportation mode and house characteristics (floor, location, recent painting, heating mode, proximity to gasoline station and proximity to busy road).
Regression predictors for pollutant/source combinations included terms consistent with a one-compartment box model for indoor concentrations, building characteristics (floor level, air exchange rate), occupant behaviors (kitchen and bathroom exhaust fan usage), and meteorological conditions (season, outdoor RH).
An indicator of socioeconomic status was constructed using a principal component analysis [ 22] based on household characteristics (flooring material, ceiling, walls, water source, sewage and number of domestic appliances).
Principal components analysis (Filmer and Pritchett 2001) was used to compute wealth quintiles from data related to household assets, including consumer items (e.g. radio, television, bicycle, etc)., and dwelling characteristics (flooring materials, type of drinking-water source, toilet facilities, etc).
A wealth indicator variable was created to represent socio-economic status based on questions assessing a woman's household ownership of specific items (radio, television, bicycle, phone, refrigerator, scooter, automobile) as well as household characteristics (flooring and roofing materials, water sources, toilet facilities, electricity).
Notochord defects were scored by absence of a morphologically recognizable notochord structure and lack of characteristic floor plate morphology, lack of Foxa2 protein expression in neural plate midline, and lack of detectable Brachyury or Shh protein expression.
The prototype was found to be capable of measuring the described frictional characteristics of floor surfaces, using three different test wheels and two modes of operation, impact and non-impact testing.
Remaining home characteristics, including floor area, heating types, and number of stories by region, were gathered from RECS [ 12].
†First principal component of household asset and characteristics: dirt floor, solid walls, crowding index, home ownership, sewage, and ownership of car, computer, blender, fridge, washing machine, and cellphone.
The index assessed housing characteristics including floor, wall and roof material; ownership of agricultural land, livestock, herds and other farm animals; and household assets including televisions, radios, clocks, fans, and mobile and non-mobile phones.
Important site variables influencing vegetation were canopy cover, pH, and forest floor characteristics.
