Please can anyone show me how can I use a summary method but include only items that are visible after using a filter.
Thanks in advance
You would have to create another line item that shows filtered data only. You can use a formula like this - "If <filter condition> then <source data> else 0". Then the summary of the newly created line item will show you the sum of filtered items.
However, if your filtering is by user dimension, then this module will also need to be by user dimension and will tend to increase in size.
Summary Items are applicable to all of the items, it doesn't work selectively or on filters.