Display running totals in SSRS in a shape of triangle for Los Development (Loss Triangle) report

Question

I need to make numbers cumulative total in a shape of triangle.

Vertical Month-Year is EffectiveDate Horizontal Month-Year is LossDate

Should be like this:

Using SSRS Expression I am able to get cumulative :

=RunningValue(Fields!PolicyCount.Value, SUM, "TablixName")

But it gives me this:

How should I write my logic to eliminate number 11 in cell Feb-17

eliminate Apr-18 and so on? Basically to make it triangle?

Data sample:

Answer 1

You need to change the scope of the RunningValue() expression

from this

=RunningValue(Fields!PolicyCount.Value, SUM, "TablixName")

to use the name of your RowGroup, not the name of the tablix.

In my test I called the Row Group EffRowGroup as you can see here..

So the Final expression looked like this..

=RunningValue(Fields!PolicyCount.Value, SUM, "EffRowGroup")

We do this so that the running value is only evaluated within the context of the row group.

Here are the results.

1. The base data
2. Your original expression
3. The final expression