You've already created the parameters you need for this calculation, just missing the calculation to use in the filter. Something like this should work:
They key part is the rank - window_max(rank)..... etc section as that reverses the values of your rank field so that you can select bottom N using the same calculation that works for top N.
Hope that helps
Speed (Top Bottom N).twbx 31.3 KB
That's awesome. Thanks Steve!
You're very welcome.