The concurrent decline of soil lead and children's blood lead in New Orleans.

Lead (Pb) is extremely toxic and a major cause of chronic diseases worldwide. Pb is associated with health disparities, particularly within low-income populations. In biological systems, Pb mimics calcium and, among other effects, interrupts cell signaling.

Spatiotemporal exposome dynamics of soil lead and children's blood lead pre- and ten years post-Hurricane Katrina: Lead and other metals on public and private properties in the city of New Orleans, Louisiana, U.S.A.

Background: Anthropogenic re-distribution of lead (Pb) principally through its use in gasoline additives and lead-based paints have transformed the urban exposome. This unique study tracks urban-scale soil Pb (SPb) and blood Pb (BPb) responses of children living in public and private communities in New Orleans before and ten years after Hurricane Katrina (29 August 2005).

Objectives: To compare and evaluate associations of pre- and ten years post-Katrina SPb and children's BPb on public and private residential census tracts in the core and outer areas of New Orleans, and to examine correlations between SPb and nine other soil metals.

Spatiotemporal dynamic transformations of soil lead and children's blood lead ten years after Hurricane Katrina: New grounds for primary prevention.

Background: The contribution of lead contaminated soil to blood lead, especially as it is a large reservoir of lead dust, has been underestimated relative to lead-based paint. On 29 August 2005 Hurricane Katrina flooded and disrupted habitation in New Orleans. Soil and blood lead were mapped prior to Katrina.

Evolving from reactive to proactive medicine: community lead (Pb) and clinical disparities in pre- and post-Katrina New Orleans.

In 2012 the U.S. Centers for Disease Control (CDC) set the blood Pb reference value at ≥5 µg/dL.

Environmental and health disparities in residential communities of New Orleans: the need for soil lead intervention to advance primary prevention.

Urban environments are the major sites for human habitation and this study evaluates soil lead (Pb) and blood Pb at the community scale of a U.S. city.

The continuing impact of lead dust on children's blood lead: comparison of public and private properties in New Orleans.

Background: Compared with a maximum collective lead (Pb) estimate of ∼1811 metric tons (MT) in exterior paint on 86,000 New Orleans houses, Pb additives in gasoline were estimated at ∼12,000 MT in New Orleans, yielding ∼9100 MT Pb exhausted as aerosols from vehicles; ∼4850 MT were particles>10 μm and ∼4200 MT were particles <0.25 μm.

Objectives: To evaluate pre-Hurricane Katrina soil Pb and children's blood Pb at public housing and private residential properties in the inner-city compared with the outer city of New Orleans.

Analysis of trend: a permutation alternative to the F test.

When the categories of the independent variable in an analysis of variance are quantitative, it is more informative to evaluate the trends in the treatment means than to simply compare differences among the treatment means. A permutation alternative to the conventional F test is shown to possess significant advantages when analyzing trend among quantitative treatments in a one-way analysis of variance. An example with and without an extreme data point illustrates the effectiveness of the permutation alternative for the analysis of trend when homogeneity of variance is compromised.

Soil intervention as a strategy for lead exposure prevention: the New Orleans lead-safe childcare playground project.

The feasibility of reducing children's exposure to lead (Pb) polluted soil in New Orleans is tested. Childcare centers (median = 48 children) are often located in former residences. The extent of soil Pb was determined by selecting centers in both the core and outlying areas.

Multiway contingency tables: Monte Carlo resampling probability values for the chi-squared and likelihood-ratio tests.

Monte Carlo resampling methods to obtain probability values for chi-squared and likelihood-ratio test statistics for multiway contingency tables are presented. A resampling algorithm provides random arrangements of cell frequencies in a multiway contingency table, given fixed marginal frequency totals. Probability values are obtained from the proportion of resampled test statistic values equal to or greater than the observed test statistic value.

Maximum-corrected and chance-corrected measures of effect size for the Mantel-Haenszel test.

Two measures of effect size are described for the Mantel-Haenszel test. Both measures belong to the r-family of effect size measures. One measure is based on a maximum-corrected model, and the second measure is based on a chance-corrected model.

Soil arsenic surveys of New Orleans: localized hazards in children's play areas.

Arsenic (As) ranks first on the 2005 and 2007 hazardous substances priority lists compiled for the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). This study describes two New Orleans soil As surveys: (1) a survey of composite soil samples from 286 census tracts and (2) a field survey of soil As at 38 play areas associated with the presence of chromated-copper-arsenate (CCA)-treated wood on residential and public properties. The survey of metropolitan New Orleans soils revealed a median As content of 1.

Stuart's tau measure of effect size for ordinal variables: some methodological considerations.

The reporting of measures of effect size has become increasingly important in psychology. A Monte Carlo resampling permutation procedure is introduced to find near-optimum maximum values for Stuart's tau(c) measure for two-way ordinal contingency tables, also termed Kendall's tau(c) since Kendall introduced tau(a) and tau(b). Comparisons between resampling and exact procedures demonstrate the accuracy and utility of resampling measures of effect size for two-way ordinal contingency tables.

Nominal-ordinal measures of association: a comparison of two measures.

The measurement of the magnitude of association between a nominal independent variable and an ordinal dependent variable is an important, but neglected, component in psychological research. Two measures of nominal-ordinal association are described and compared. Resampling permutation methods are utilized to compute probability values for both measures.

Resampling permutation probability values for Cronbach's alpha.

A permutation procedure to compute a resampling probability value and empirical quantile limits is provided for Cronbach's alpha measure of internal reliability. The underlying assumptions for the conventional use of alpha are discussed. The use of a permutation test for Cronbach's alpha is highlighted as a valuable tool when sample sizes are small and necessary assumptions cannot be met.

Weighted kappa for multiple raters.

Five procedures to calculate the probability of weighted kappa with multiple raters under the null hypothesis of independence are described and compared in terms of accuracy, ease of use, generality, and limitations. The five procedures are (1) exact variance, (2) resampling contingency, (3) intraclass correlation, (4) randomized block, and (5) resampling block. While each procedure possesses strengths and limitations, the resampling contingency procedure is shown to be the most versatile and accurate of the five procedures, provided the number of raters is not too large.

Resampling permutation probability values for weighted kappa.

A permutation algorithm and associated FORTRAN program are provided for resampling weighted kappa. Program RWK provides the weighted kappa test statistic and the resampling one-sided upper-tail probability value.

Resampling probability values for weighted kappa with multiple raters.

A new procedure to compute weighted kappa with multiple raters is described. A resampling procedure to compute approximate probability values for weighted kappa with multiple raters is presented. Applications of weighted kappa are illustrated with an example analysis of classifications by three independent raters.

Exact permutation probability values for weighted kappa.

A permutation algorithm and associated FORTRAN program are provided for weighted kappa. Program EWK provides the weighted kappa test statistic and the exact one-sided upper-tail probability values.

Permutation tests: precision in estimating probability values.

The number of resamplings necessary to accurately estimate a probability value is an open question. One million resamplings is shown to be sufficient to ensure precision to three places under most conditions.

The exact variance of weighted kappa with multiple raters.

Weighted kappa described by Cohen in 1968 is widely used in psychological research to measure agreement between two independent raters. Everitt then provided the exact variance for weighted kappa for two raters. In this paper, Everitt's exact variance is extended to three or more raters.

Resampling programs for multiway contingency tables with fixed marginal frequency totals.

A resampling algorithm is presented for analyzing multiway contingency tables with fixed marginal frequency totals. Applications are illustrated with extensions of Fisher's exact, Pearson's chi-squared, and likelihood-ratio tests to three-way contingency tables.

Nonlinear association between soil lead and blood lead of children in metropolitan New Orleans, Louisiana: 2000-2005.

Metropolitan New Orleans is unique because it has a universal blood lead (BL) screening dataset (n=55,551) from 2000-2005 spatially coupled with a soil lead (SL) dataset (n=5467) completed in 2000. We evaluated empirical associations between measurements of SL and BL exposure responses of children in New Orleans by stratifying the databases by Census Tracts and statistically analyzing them with permutation methods. A consistent curvilinear association occurred annually between SL and BL with robust significance (P-values<10(-23)).

An alternative measure of effect size for Cochran's Q test for related proportions.

Measures of effect size are increasingly important in psychological research. In this paper, a chance-corrected measure of effect size is introduced for Cochran's Q test.

Resampling permutation probability values for six measures of qualitative variation.

An algorithm and associated FORTRAN program are provided for six common measures of ordinal association: Kendall's taua and taub, Stuart's tauc, Goodman and Kruskal's gamma, and Somers' dyx and dxy. Program ROMA reports the observed data table, the values for the six test statistics, and the resampling upper- and lower-tail probability values associated with each test statistic.

Urban soil-lead (Pb) footprint: retrospective comparison of public and private properties in New Orleans.

Lead (Pb) is a toxin that after childhood exposure poses a lifetime of health risks. One route of exposure is soil-Pb as a result of 12 million metric tons of Pb residue in paint and gasoline sold in the US during the 20th Century. Pb accumulated in soil of the community is a good predictor for blood Pb of children living there.