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Summary: A common problem in educational evaluation is estimating causal effects of interventions from non‐experimental data on students. Scores from standardized achievement tests often are used to adjust for differences in background characteristics of students in different non‐experimental groups. An open question is whether, and how, these adjustments should account for the errors in test scores as measures of latent achievement. The answer depends on what information was used to assign students to non‐experimental groups. Using a case‐study of estimating teacher effects on student achievement, we develop two novel empirical tests about what information is used to assign students to teachers. We demonstrate that assignments are influenced by both information that is unobserved by the researcher, and error prone test scores. We develop a model that is appropriate for this complex selection mechanism and compare its results with common simpler estimators. We discuss implications for the broader problem of causal modelling with error prone confounders. [ABSTRACT FROM AUTHOR]

Identifying the environmental features affecting gene flow across a species range is of extreme importance for conservation planning. We investigated the genetic structure of the Egyptian mongoose (Herpestes ichneumon) in Western Iberian Peninsula by analyzing the correlations between genetic distances and landscape resistance models. We evaluated several functional relationships between elevation, vegetation cover, temperature, and genetic differentiation under the original and reciprocal causal modelling approaches. Additionally, we assessed evidence of isolation-by-distance (IBD) in the mongoose population. Original causal modelling identified IBD as the best model explaining genetic patterns in the mongoose population. By contrast, reciprocal causal modelling supported high shrub cover at middle elevations as the best model explaining species gene flow. The results from reciprocal causal modelling demonstrate that the Egyptian mongoose is dependent of ecosystems dominated by Mediterranean shrub cover. Recent land-use changes related to rural abandonment promoted the growth of shrub areas, especially at middle elevations, facilitating genetic connectivity in the mongoose population in those areas, where anthropogenic activities are less intense. The present study should be considered as a model for landscape genetics studies of Mediterranean carnivores in the Iberian range with the aim of better understanding how recent land-use changes affect a broad guild of species. [ABSTRACT FROM AUTHOR]

Although habitually considered as a whole, xylogenesis is a complex process of division and maturation of a pool of cells where the relationship between the phenological phases generating such a growth pattern remains essentially unknown. This study investigated the causal relationships in cambium phenology of black spruce [Picea mariana (Mill.) BSP] monitored for 8 years on four sites of the boreal forest of Quebec, Canada. The dependency links connecting the timing of xylem cell differentiation and cell production were defined and the resulting causal model was analysed with d-sep tests and generalized mixed models with repeated measurements, and tested with Fisher’s C statistics to determine whether and how causality propagates through the measured variables. The higher correlations were observed between the dates of emergence of the first developing cells and between the ending of the differentiation phases, while the number of cells was significantly correlated with all phenological phases. The model with eight dependency links was statistically valid for explaining the causes and correlations between the dynamics of cambium phenology. Causal modelling suggested that the phenological phases involved in xylogenesis are closely interconnected by complex relationships of cause and effect, with the onset of cell differentiation being the main factor directly or indirectly triggering all successive phases of xylem maturation. [ABSTRACT FROM PUBLISHER]

Background. Declining residual renal function, as indicated by the glomerular filtration rate (GFR), is associated with an increased mortality risk in patients with end-stage renal disease (ESRD) on dialysis.Methods. We monitored GFR and mortality in 1800 haemodialysis (HD) and peritoneal dialysis (PD) patients in 1996–2006. We used a marginal structural model to estimate the causal effects both of GFR when it was not completely lost and of the subsequent full loss of GFR on mortality, avoiding the drawbacks of standard regression models that include covariates to adjust for confounding. Instead, effect estimates were adjusted for possible baseline and time-varying confounders using inverse probability weighting.Results. We estimated a hazard ratio (HR) corresponding to the effect of the full loss of GFR on mortality, as compared to not having fully lost GFR, of 1.50 [95% confidence interval (CI) 1.09–2.07]. The HR corresponding to the effect of GFR when GFR is not (yet) fully lost on mortality was 0.97 (95% CI 0.92–1.02) (per mL/min/1.73m2). We found no significant difference in the effect of GFR on mortality between patients starting on PD and HD.Conclusions. Preventing or delaying the full loss of GFR can improve survival in dialysis patients. This supports the importance that is given to the effect of treatment options for patients with ESRD on the rate of decline of the residual renal function. [ABSTRACT FROM PUBLISHER]