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Table 3 Multivariate regression models of excess death rates associated with the spring, fall, and winter pandemic waves as a function of socio-demographic variables across provinces of Spain

From: Spatial-temporal excess mortality patterns of the 1918–1919 influenza pandemic in Spain

Spring wave
Predictor Coefficient Standard error P value RMSE Intercept Predictor is in final model?
Baseline mortality rates 0.884 0.073 <0.001 1.31 −0.7852 Yes
Latitude −0.017 0.074 0.822    No
Longitude −0.041 0.058 0.478    No
Population density 0.004 0.006 0.505    No
Population size 0.000 0.000 0.764    No
Proportion of school age children 5–15 years 7.336 9.547 0.446    No
Infant mortality rates 0.002 0.002 0.168    No
Urbanization 0.049 0.015 0.002    Yes
Fall wave
Predictor Coefficient Standard error P value RMSE Intercept Predictor is in final model?
Baseline mortality rates −0.68 1.55 0.67 29.8 −315.1 No
Latitude 7.02 1.61 <0.001    Yes
Longitude 0.21 1.76 0.90    No
Population density −0.20 0.11 0.08    Yes
Population size 0.00 0.00 0.42    No
Proportion of school age children 5–15 years 403.45 205.47 0.06    Yes
Infant mortality rates −0.02 0.03 0.60    No
Urbanization −0.21 0.46 0.65    No
Winter wave
Predictor Coefficient Standard error P value RMSE Intercept Predictor is in final model?
Baseline mortality rates 0.754 0.048 <0.001 1.86 −2.5 Yes
Latitude −0.121 0.109 0.275    No
Longitude −0.048 0.085 0.573    No
Population density 0.005 0.008 0.548    No
Population size 0.000 0.000 0.462    No
Proportion of school age children 5–15 years −14.092 12.843 0.278    No
Infant mortality rates 0.005 0.002 0.014    Yes
Urbanization 0.009 0.022 0.699    No
Cumulative excess rates
Predictor Coefficient Standard error P value RMSE Intercept Predictor is in final model?
Baseline mortality rates −0.579 0.563 0.310    No
Latitude 7.082 1.528 <0.001    Yes
Longitude 0.050 1.674 0.976    No
Population density −0.196 0.105 0.070    Yes
Population size 0.000 0.000 0.380    No
Proportion of school age children 5–15 years 395.934 195.292 0.049    Yes
Infant mortality rates −0.001 0.033 0.972    No
Urbanization −0.090 0.439 0.839    No
  1. We generated simplified models by means of backward stepwise elimination. Predictors in final simplified models for each pandemic wave are highlighted in bold. Coefficients, standard errors, and P values for all other predictors correspond to the full regression model.