You can tell how well your outreach is doing by seeing how attendance changes over time. You can tell how current events impact attendance. That’s both internal and external. Current events sometimes drives people to faith. Internal conflicts sometimes drive them away. My meeting’s assistant clerk said she wished she knew if the “this current conflict is making people stay away” talk my meeting had going on earlier this year was accurate. Well, I personally did head counts, so I could tell her the trends. None of that’s written anywhere, though.