Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Doctor volunteers for rejuvenation procedure
S18E2
·
The Leisure Hive Part 2
To
Romana sees the melting hourglass
S18E2
·
The Leisure Hive Part 2
Why These Connect
The narrative assertion
"Romana's decision to activate the recorder in the Tachyon Lab is a direct result of the Doctor preparing for rejuvenation, and her later discovery of the hourglass malfunction is triggered by her presence in the lab during the procedure."
About Causal Connections
A directly causes B. The first event sets forces in motion that produce the second. These are the load-bearing connections of plot--remove one and the story structure collapses.