BTW, Mayor Bloomberg instituted this service for all non-emergency calls to the City. right after he first became mayor. It was modeled it after the help desk for the Bloomberg Terminal. That service was pretty much the best help desk I have ever dealt with. Extremely focused on metrics.
You aren't stupid, but probably haven't encountered a streamgraph[1] before. It's just a stacked area graph where X is time (it's even labeled at the top) and Y is frequency of calls (thickness, not from the origin). I think it's an excellent and informative graphic, personally.
I dunno. The graphic seems pretty straight forward. The entire width of the band is the total number of calls received, and the categories of calls make up the components of the band. Wider band of color means more calls received.
But what is it actually straight forward about? All that can be gleaned from this particular graph is that there are a lot of noise complaints at night, a lot of streetlight complaints around noon, and that there's a larger variety of complaints during the day. The rest is just pretty visual noise. Consider the humps and valleys that occur when following the sections for "consumer complaints"... The rising and falling of that line means absolutely nothing, yet it obscures the line's own thickening and thinning to the point where it's pretty useless.
A simple line chart (while not as pretty) would be even easier to read and much more useful. You'd still see the major trends you see in this chart, but the rest of the information would be useful instead of just noise.
I don't think the graph is supposed to be particularly useful to you, I think this graph is more useful to the actual city workers so they can focus on specific complaints at specific times.
There's no point focusing on streetlight complaints at 6pm, and there's no point focusing on noise at 7am when the garbage trucks are going around.
Deal with the right problems at the right time gets a much better response from your customers (IE the tax payers and voters).
In general you want to deal with the vast majority of complaints. The rising and falling of the line is caused by something else becoming larger.
You don't follow the line itself, but judge its thickness by placement on the X-axis.
I think Tufte comments on this type of graph (or a similar type), but I don't have a copy of the book handy. Would anyone who does like to share what he says?
I didn't know there was a number you could call to let the city workers know something is not right in NYC. It's one of the things I really want to have in my city because most of the times I don't know who to call.
Examples: dead animal, street sign on the floor, noise, etc. Sometimes I call the police but they just don't care about stuff like this...
That is something I like about cities getting Twitter accounts. I love being able to hop on Twitter and type up a quick message to @CityOfAmes to complain about construction or trees down in parks.
It's interesting that people call about streetlights in the middle of the day, although they presumably notice the problem when it's dark, but they complain about noise right when it is occurring.
The graph actually shows a separate item for "traffic signal conditions", which implies that "streetlights" are in fact different than traffic signals. (Look at the middle/upper-right; it's kind of hard to see).
Probably that is because of calls made during lunch breaks. Or the complaints could be about streetlights that are on during the day rather than off/broken at night.
Why is there a bump in traffic signal conditions at 15:00, that doesn't follow the bump in street conditions at 19:00?
The latter I assume is because by that time, everyone has driven home from work, noticed problems, and phoned about them when they got home. But why only street conditions? Why not traffic signals?
15:00 could be the switch to rush-hour signalling. I know where I live it screws up turn-lights and pedestrian crossing lights. I've seen turn lanes getting a single car through at every light change, it's gotten so bad that it clogs up one of the through-lanes. Similarly there's rarely a single pedestrian at a crossing, and I've been forced to J-walk because the pedestrian crossing hasn't come on for several light changes.
