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The curious case of disappearing buses
Nice investigation into some dodgy pseudo-real-time bus location data in the Bristol real time passenger information system (via Tony Finch)
So what have we learned? One thing we are sure is that data of different qualities – genuinely real-time, pseudo real-time (Type 2 and Type 1), and non-real-time (scheduled) data – all present in the data stream.

Among these the most interesting are Type 2 pseudo real-time data. They appear to be the root cause of the phenomenon of disappearing buses.

Type 2 pseudo-real-time data are not totally bogus. One possible explanation of their existence can be this. The bus company has limited but not full tracking information on some of their buses. For example, it may know the location of a bus only when the bus leaves the bus terminal. Instead of not showing any data at all about the bus, the bus company uses interpolation to predict the locations of the bus, and reports these as if those are real-time data.
via:fanf  bristol  buses  public-transport  rtpi  estimation  open-data 
2 days ago by jm
[1901.03403] Mean Estimation from One-Bit Measurements
We consider the problem of estimating the mean of a symmetric log-concave distribution under the following constraint: only a single bit per sample from this distribution is available to the estimator. We study the mean squared error (MSE) risk in this estimation as a function of the number of samples, and hence the number of bits, from this distribution. Under an adaptive setting in which each bit is a function of the current sample and the previously observed bits, we show that the optimal relative efficiency compared to the sample mean is the efficiency of the median. For example, in estimating the mean of a normal distribution, a constraint of one bit per sample incurs a penalty of π/2 in sample size compared to the unconstrained case. We also consider a distributed setting where each one-bit message is only a function of a single sample. We derive lower bounds on the MSE in this setting, and show that the optimal efficiency can only be attained at a finite number of points in the parameter space. Finally, we analyze a distributed setting where the bits are obtained by comparing each sample against a prescribed threshold. Consequently, we consider the threshold density that minimizes the maximal MSE. Our results indicate that estimating the mean from one-bit measurements is equivalent to estimating the sample median from these measurements. In the adaptive case, this estimate can be done with vanishing error for any point in the parameter space. In the distributed case, this estimate can be done with vanishing error only for a finite number of possible values for the unknown mean.
statistics  estimation 
4 weeks ago by arsyed
#NoEstimates isn't crazy
We always could stop estimating, but it’s not always the right thing to do. It’s always legitimate to think about it.
software  estimation 
5 weeks ago by rtlechow
PragPub February 2013 | Estimation is Evil | The Pragmatic Bookshelf
To no one’s surprise, having been overloaded, the team falls short. Nonetheless, management tells the team that they need to improve their estimates. What management really means is that estimates are promises—even forced estimates—and the team needs to keep their “promises,” even if they never promised. The team accomplishes all that it can accomplish. Then management tries to force the team to do more than they can do, demanding that the team “become more productive,” which means “go faster, promise more, and get it done.”
software  estimation 
5 weeks ago by rtlechow
How much does a website cost in 2019?
Estimate the costs of a new website with this free calculator. Adjust design, CMS, SEO, and support options to arrive at your perfect budget.
budget  business  agency  website  pricing  cost  costs  estimation  internet  price 
5 weeks ago by atran
How much does a website cost in 2019?
Estimate the costs of a new website with this free calculator. Adjust design, CMS, SEO, and support options to arrive at your perfect budget.
pricing  tool  product  estimation 
5 weeks ago by richardsison

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