Typically, the chart type remains the same at all levels but there are a number of cases where the type of data analysis needed changes from one level to another. For example, you are displaying sales comparison starting with a column chart for comparing the annual sales over 3 years and these columns can be drilled down into for showing the monthly comparison for that year. Now for the monthly comparison, if you want to highlight the overall trend of sales rather than individual figures, you would need a line chart instead of the column chart. Once you know the chart type required at each level, you can plan the layout and the space required accordingly.