Intraregional between-household variability accounted for 24 48% of the total variability in residential-dust PAH measurements, and between-household variability was greater for heavier PAHs (e.g., benzo[ k]fluoranthene) compared with lighter PAHs (e.g., phenanthrene).
For each PAH, total variance was apportioned into regional variability (1 9%), intraregional between-household variability (24 48%), within-household variability over time (41 57%), and within-sample analytical variability (2 33%).
The variance ratio (i.e., the ratio of the sum of the within-household variability over time and the within-sample analytical variability to the sum of the regional variability and the intraregional between-household variability) ranged from 0.9 to 3.0.
In model 4, including smoking habits, residential construction date, residence type, shoe removal habits, carpet coverage, residential square footage, and heating practices (i.e., residential covariates) explained 5 27% of the intraregional between-household variability in residential-dust PAH concentrations.
In model 6, including each of the neighborhood, residential, and temporal covariates explained 59 100% of the regional variability, 3 28% of the intraregional between-household variability, and –4 to 14% of the within-household variability in residential-dust PAH concentrations over time.
We assume b h, b hi, b hij, and e hijk are mutually independent and normally distributed random variables, with means of zero and variances of σ BR, σ BH, σ WH, and σ WS, representing the between-region variability, the intraregional between-household variability, the within-household variability over time, and the within-sample analytical variability, respectively.
Intraregional differences between households were associated with the residential construction date and the smoking habits of residents.
This increased antibody specificity for three highly immunogenic salivary proteins, in part, accounts for the lack of statistical significance in testing differences between intraregional profiles for Jordanian donors.
These data indicate that while intraregional gray matter may be considered homogenous, there exists heterogeneity between differing regions of the brain.
However, some intraregional differences were as large as mean decline in sperm density between 1938 and 1990, and recent reports from Europe and the United States further support large interarea differences in sperm density.
Intraregional comparisons are limited by the fact that case definitions and surveillance systems vary between countries.
