This is possible, although there must be an easier way than they way I've done it. I had to create a couple of calculated fields and a parameter to achieve the desired result but don't have the time right now to see if there's a better way to do this. Perhaps some of the experts on this forum will supply a neater solution.
Firstly I create a calculated field to count the number of employees in 2010. I had to create this as a Table Calculation as I believe filtering based on a table calc filters only the results and not the source data. I called the field 2010EmployeeCount and the formula I used is: WINDOW_SUM(SUM(IF [Year] = 2010 THEN [Employees] END)).
Next I created a simple parameter, MinEmployee2010, so the user can enter the minimum employees required in 2010 for the company to appear in the report.
The final step is to create a calculated field, 2010EmployeeFilter, to be the filter combining the calculated field and the parameter. This is IF [2010EmployeeCount] >= [MinEmployees2010] THEN 1 ELSE 0 END.
Drag this pill to the Filters shelf and set the value to be a minimum of 1 and it will only display those companies with a 2010 employee count greater than or equal to the number selected in the parameter.
I've attached the twbx file for reference. Hope it works for you. I've also written a blog post showing how a table calculation filters only the results and not the underlying dataset.
Message was edited by: Andrew Watson
Many thanks for your help - I was slower to implement it than you were to create it
And thanks also for being so reactive!