Values are constantly changing and being updated in your Marketo database. Sometimes instead of looking for a specific value, you want to look for people that have had a change in value. Here's how.
1. Go to the Marketing Activities area.
2. Select the smart list and click the Smart List tab.
3. Find the Data Value Changed filter and drag it onto the canvas.
4. Set Attribute to the field you want to look for data value changes on.
This filter will look for all people that had a change (any change) to their Status. If you want to get even fancier, try adding a constraint to a smart list filter.