For the purpose of our analyses, se

For the purpose of our analyses, seasonal index graphs were
designed to highlight the monthly seasonality of any bacterial contamination in each commodity group. Supplementary seasonal index graphs were produced when the seasonal index graph for the whole commodity showed a seasonal effect with a variation greater than 0.01, indicating a statistically significant influence (i.e., significantly different at the 95% confidence level, based on a dummy variable model). These graphs aim to compare the seasonal variations between commodity sub-groups, such as domestic vs. imported products, conventional vs. organic production and the geographical regions where the products were sampled.
Three conclusions may be drawn from the seasonal indices: