4 ms·
This is a nice analysis, but the data in the article actually disproves it, at least to the degree show in the last plot (quite reliably in my opinion). The dis
by foobar2020 12y ago
This is a nice analysis, but the data in the article actually disproves it, at least to the degree show in the last plot (quite reliably in my opinion). The distribution of the waiting time is exponential, is a Poisson process, which means that buses do not influence each other.
- stdbrouw 12y agoThe existence of one plausible explanation (good model fit) does not automatically invalidate another plausible explanation (mechanism of action).
- foobar2020 12y agoIt does if the explanations are contradictory. In this case this means one of two things: 1) The "first bus collects delay" theory is responsible for a part of the difference between the data and the model, after all there is some. 2) There is another mechanism at action that statistically reverses the effect of the "first bus collects delay" theory, not necessarily in the same bus runs. Number 1) is coherent with Occam's razor.
- barrkel 12y agoThe mechanism is real and I've seen it in action, to the point that two buses can end up leap-frogging one another as they make their way along a route, the later bus becoming the earlier bus, but getting bogged down on the next stop, and so on. Glommed together like that, they rarely come apart. If the data doesn't support that - and I haven't the time to analyze the analysis to determine if it doesn't - it's probably due to actions TfL take to counter it. Buses don't stop as often to "even out gaps in the service" as the tube does, but standing at bus stops, I frequently see buses "disappear": two buses look like they're going to arrive at the same time, but one of them turns into a different bus, like it's been reallocated.
- fragmede 12y agohttp://en.wikipedia.org/wiki/Bus_bunching http://en.wikipedia.org/wiki/Bus_bunching is a real, studied thing.