Showing the average on a chart in Business Objects

In my latest courses, lots of folks had questions about the way Contexts work. So, here’s another way, contexts are used :

You want to show the average of something on a chart, as a horizontal line. That means, you will have to create a column with that average in a table, where the same number is shown in the entire column.

Month	N° visitors	Average
1	25	25
2	100	100
3	72	72
4	97	97
5	93	93
6	103	103
7	111	111
8	23	23
9	87	87
10	98	98
11	39	39
12	111	111
Average	79,9

It’s pretty clear, the formula =Average(<N° visitors>) won’t do the trick. It just returns the number itself, because it operates in the context of the month. To solve this, we can use 2 formulas :
Average(<N° visitors>) in Report
Average(<N° visitors>) forall(<Month>)
The first one is absolute, so it will always return the same number – no matter in which table you put it. The second one is relative – it depends on the dimensions already in the table.
One way to do this is by choosing : Data> Define as variable and choosing Evaluate the formula in its context.



Both of the above will return :

Month	N° visitors	Average
1	25	79,9
2	100	79,9
3	72	79,9
4	97	79,9
5	93	79,9
6	103	79,9
7	111	79,9
8	23	79,9
9	87	79,9
10	98	79,9
11	39	79,9
12	111	79,9
Average	79,9

Now, we turn this into a chart :



Not exactly what we need, but, getting there.

Rightclick the chart and choose “Format Chart”
On the Series tab, click “Add” and make it a line chart, next, you drag the average from the other group to the new group.



And we get :


Cheers folks

Binabik