I don't want answering the question "how is your day going?" to take more than the 2 seconds it takes to move your mouse to the link.
The problem with the slider is that you have you interface with it. So the workflow would be: get an email, click a link, move a slider (compared to get an email, click one of 3 links). I know I'd want to avoid the extra step as a user, so that's why I opted for that approach.
There is also an option for the user to enter an anonymous comment after they have logged their mood - so if you want to express why today is bad or add note that it is an especially excellent day you can do that.
At a higher level view, I think the value in this particular app is not a scientifically rigorous computation of a teams mood, but rather as a conversation starter ("why has there been a few 'bads' this week? let's talk about it") and a general trend indicator ("morale is down since we moved to the new office, what's up with that?").
It's a good point that you can't do a slider in email, I didn't think of. Unless email allows embedding an html form that you can submit? I've never seen anything more than static html in my email so I guess it must not be possible.
Anyway, thanks for your explanation, it makes sense. I think I'll make myself a 0-1 floating point favourites tracker and see how I like using it.
Thanks for the feedback, I appreciate it.
I built a political survey app once, and we started out using sliders to measure both (1) issue importance and (2) agree/disagree. It was way too fiddly, and no one cared about degree of accuracy. Every iteration of the UI we gave the user fewer choices. By the end I was pushing for just "agree" and "disagree" or even "agree" and "next question," but we never took it quite that far.
I find this very interesting. What made you want to avoid use a slider?
Personally, I really dislike such limiting options. Good, meh, bad? It doesn't let me express if I'm a little better than good or somewhere between Good and Meh. I'd often have to truncate my true expression.
For myself, I would love a single simple slider. It would let me express myself with any degree of accuracy I want. Very specific, or just rough.
Am I an exception from the average user?
Because this bugs me in so many places. So many things are in or out. I want them to be a floating point value between 0 to 1. Website favourites. I wish I could favourite them by any amount between 0 to 1, etc. (Then you could do all sorts of things like display the higher-ranked items larger, or filter displaying only >= 0.75 items). Same goes for app/movie rankings. Why do I have to truncate my feelings to 1-5 stars instead of just dropping a slider to where I feel like?