Almost all growth within the borg falls in two major categories:
Baptized children of current JWs
Non-JW spouses and family members moving into JW households (retired or disabled parents, etc.) who convert to keep the peace
One other category that I keep tripping across that encompasses most non-JW related converts is due to personal tragedy:
"My husband had just been killed in a car accident. That very next weekend two nice JW ladies came to my door and offered me a free Bible study and explained how I could someday be with my husband again..." and others like that.
Also in this category are the co-worker or fellow student converts:
"My marriage was breaking up (or, my parents had thrown me out of the house) and I was desperate. Co-worker JW noticed that I was distressed and joined me for lunch and told me there was a place where I could get support and new friends. I finally decided to go to the Kingdom Hall and immediately felt welcomed and loved ("love-bombing" by the book). Everyone was so nice to me...etc."
My websites get a lot of emails that are either from leaving JWs who tell these stories about how they got hooked, or by newly converted JWs who are trying to convince me that JWs are really the good people they claim to be and that I am just printing lies about the Watchtower.
I don't think (other than in convention demonstrations) I've ever seen a case where a new JW was converted because the JWs convinced them during a door to door encounter or a formal Bible study. In fact, everyone that I've met that actually agreed to have a "free Bible study" ended that type of association between the 2nd or 5th study meet. Remember that a lot of Bible Studies reported on the annual report are actually family Bible studies with unbaptized spouses and children who have no choice but to convert.
That's not to say that no one has ever been converted due to a door-to-door visit. Richard Kelly's mother was converted that way. And Richard Kelly's mother converted my mother that way (actually through a door knock referral). But in both cases, our mothers were in desperate situations due to family tragedies or conflict. So they were vulnerable.
Those are the key words: Vulnerable or Related.
JV