I don't run a PTO, and I've never done surveys, or analyzed them, lol. Still, I sympathize.
You're doing so much advertising, I'd discount those who say they didn't know when the meetings were, etc. I suspect they're just saying that, because they don't want to say that they just don't want to go to the meetings. That makes them look bad. Or that the meetings are so far off their radar, they really don't remember them, well advertised as they are.
I go to some of the PTO meetings at my son's school, and I'll tell you frankly that I HATE them. Really. I go to a minimal number of meetings. That said, I am pretty involved in all kinds of activities.
So how to get more of an attendance? I can share some of the reasons I don't like the PTO meetings...
First, there's never anyone to greet you. If you walk in cold, and see no (or just faintly) familiar faces, it's daunting.
Our meetings are held in the cafeteria. The acoustics are TERRIBLE. I miss half of what's said, including nearly everything said from the floor (the PTO board has a mike). I never say anything, since I'm soft spoken and believe that I'd have to shout to be heard.
The whole physical set up is an invitation to snore-dom. The board members sit up front at one table, the rest of us are in this large cafeteria. There's no intimacy whatsoever, and makes this whole statement ("we're the board, you're not".) It's just uncomfortable overall.
You have to sign up to receive PTO minutes. I think this is a big mistake. Getting minutes to all members is a way to help them keep their finger on the pulse, and may slowly build up attendance.
The meeting agenda is handed out at the meeting. Another mistake, IMO. Knowing the agenda beforehand can spark interest.
If you don't attend every meeting, continued discussion on issues without recapping things can make people feel like they've walked in the middle of something, and make them lose interest.
Meetings can start late, sometimes as much as 20 minutes late, for no discernible reason. I find this VERY irritating.
Most of my complaints revolve around basic meeting management. Assuming people know when the meetings are (and that's not usually a problem), it's just:
Provide an agenda beforehand (if possible. This is not a huge thing. Post one in the school; use the email list, etc.)
Welcome people!
Start on time.
Be less formal. Formality stifles discussion. Make sure someone can rein in discussions that get out of hand.
Send minutes to people.
Express appreciation to people for coming. People will more likely come if they believe that their presence has been of some value.
Briefly recap, for newcomers, what has already transpired with ongoing discussions.
I kind of believe that huge PTO meeting attendances are a thing of the past (if they ever were hugely attended.) People are more likely to attend if their friends attend. I don't know. I attend maybe 2 meetings all year, and let me tell you, I'm ready to break for the door almost as soon as I get there, lol. Topics come up, I often have no idea of what they are talking about, I'm left wondering if I just missed what was said because the people behind me were laughing too loud. I always leave with the thought "I'll never get THAT hour back!" I have often wondered why this relic continues. With all the ways to communicate (many of which are not taken advantage of), added to the distinct impression that the real decisions are made during lively discussions elsewhere (by board members and highly involved people), this stiff, formal meeting seems to me to be a big waste of time.