"Hidden" stats, what am I doing wrong?

Title. I’d like a stat to be invisible when a player enters the choicescript_stats menu unless a certain condition is met. Say, for example…

*if (encounter_bob = “true”)
(here is a code unbeknownst to me that would be entered to display a stat, maybe like “bob_relationship” if the condition “encounter_bob” is set to “true”)
*else
(code entered here to hide “bob_relationship” if “encounter_bob” is anything other than “true”)

Any idea of how I may accomplish this? Thank you so much!