Just GA. Now that you mention it though, given all the pop-up blocking, my numbers are likely underestimated. I'll cross-reference with server logs next time.
re 6 vs. 150 subscribers. The trick to getting people to sign up is... (you are not going to like this)... a pop-up.
People on forums will complain about it.
People will sign up with fake and insulting email addresses to spite you. You may even get upset.
But my god will you gather emails from the people out there who actually care about the work you are doing.
But I am going to put the subscription form at least at the bottom of each post, and think of other ways to get it in front of people. I may consider a popup in the future if I put the work in to make sure people who are already subscribed generally don't see it. Like when they confirm their subscription, set a cookie that will block the popup. Something like that. Or a "don't show me this again" button. I didn't see a popup on your site FWIW.
EDIT: Or duh, just a URL param like show_popup=false in the notification email URL.
Anyway thanks for the feedback. I'm realizing now that I've read your posts in the past and really enjoyed them, so you have another subscriber!
With my popup, I try to wait to show it until a moment when I feel the visitor is actually interested. At first approximation, that's when they have been on the page more than 60 seconds and scrolled down more than 70%.
Like you mentioned, I also use cookies to ensure people who have already subscribed (or hit X on a previous pop-up) don't see it again.
And thanks for subscribing! I love these random encounters on HN.
How do you track visits? As mentioned elsewhere in this thread, if you're using GA I would expect it to be skewed by ad blockers from the HN crowd.