To examine the relation between changes in the consumption of
different types of alcoholic beverage and alcoholism mortality across
the study period a time-series analysis was performed using the
statistical package “Statistica”. The dependent variables were the annual
alcoholism mortality and the independent variables were aggregate
beverage-specific alcohol sales. Bivariate correlations between the raw
data from two time-series can often be spurious due to common sources
in the trends and due to autocorrelation [12,13]. One way to reduce the
risk of obtaining a spurious relation between two variables that have
common trends is to remove these trends by means of a ‘differencing’
procedure, as expressed in formula: