LITMIR.BIZ

      The first expression calculates the average margin percent, and it’s accurate – the summarized Cost of Goods Sold (COGS) is subtracted from the summarized Sales Amount, and the result is divided by the summarized Sales Amount. Conversely, the second expression, while valid syntax-wise, is logically incorrect. The margin percent calculation is enclosed in a single aggregation function, therefore it is performed at every detail line, and then the resulting percentages are summarized. Even if you replaced sum() by avg(), the result would be different from the formula above, and most likely be different from the expected result.

      To summarize this brief introduction to chart expressions, let’s emphasize the two points that you’ve just seen:

      Chart Dimensions

      If charts always show aggregated data and chart expressions define what aggregation functions should be used, then dimensions describe the level of aggregation for the chart.