Hence, confidence intervals for the mean number of badgers per social group were based on quantiles of normal distributions, and standard errors for population estimates based on combining Land Class Groups were based on a first-order Taylor series.
For the log-normal regression, the standard errors have been calculated using White's heteroskedasticity-consistent matrix, since White's test indicated possible heteroskedasticity.
For pairwise comparisons of subgroup estimates, the p-value for a two-tailed test was calculated using the normal distribution probability function PROBNORM in SAS, assuming approximate normal distribution of each individual subgroup estimates with the estimated standard errors, and approximate normal distribution for the estimated difference.
We calculated 95% CIs for standardized prevalence rates using a normal approximation and Breslow-Day standard errors, after being modified to use a binomial assumption for the variance of the crude stratum-specific rates (9).
Pseudo-random sets of fluxes were created by sampling from normal distributions with mean and standard errors equal to those of each NMR flux applied to the model.
A 95% confidence interval (CI) and two-sided P-value for testing the null hypothesis of no difference between treatment groups was performed based on the normal approximation (Z-test) with standard errors calculated by the bootstrap method.
Group comparisons were made using chi-square tests for equal proportion, Student t-tests for normally distributed data and Wilcoxon rank sum tests otherwise, with normally distributed data reported as means ± standard errors and non-normal data reported as medians (interquartile range).
Linear regression analysis was applied to each database to characterize the age decline observed in normal subjects; the standard error of the regression was used to define the 95% CI limits of the measured SBRs.
Several procedures (i.e. Shapiro-Wilk normality test, kurtosis and skewness and a z-score obtained by dividing the skew values or excess kurtosis by their standard errors) to evaluate normal distribution of cognitive and behavioural variables.
A logarithmic transformation was applied to the HR (SD) to form normal distributions (see Table 5 means, standard errors, and F values).
