2 min read

2018-07-15 Links

Telescope details you never knew

“I disagree with the other answers that say this is only important for astrophotography. Think of it this way, the focal ratio is basically a measure of how steep the light cone is inside the telescope. There are a significant number of ways this impacts even visual viewers.”

Machine learning in risk management

“The new model allows for the elicitation and exploitation of prior knowledge and experts’ judgements, and for the constant update of this information over time, as soon as new data become available. We show how to use it to perform Bayesian nonparametric prediction about the recovered amounts and the (total) recovery time of a series of defaulted exposures. An application to real data is provided using the Single Family Loan-Level Dataset by Freddie Mac.”

Street orientation in major U.S. cities

“How coherent is a city’s spatial organization? How do these patterns help or hinder urban navigation? I recently wrote about visualizing street orientations with Python and OSMnx. That is, how is a city’s street network oriented in terms of the streets’ compass bearings? How well does it adhere to a straightforward north-south-east-west layout?”

Tenant mix and mall traffic with Foursquare data

“We studied malls with venues that opened in 2016 and followed foot traffic trends over the next four quarters, while correcting for seasonality. This approach allowed us to compare venues that opened in different quarters. Full caveat: While we found meaningful statistical correlations, we know that that doesn’t necessarily indicate causation. Do arcades drive more traffic to malls? Or are arcade operators just good in picking malls growing in popularity? Perhaps there was an underlying third cause. We believe the opening may be causational in the cases where we’ve chosen to highlight trends or disclose the specific lift we’ve seen.”

Is Yolanda gonda?

“For years, Yolanda’s Little Black Book has been one of the biggest mysteries in Los Angeles luxury real estate circles. By gleefully revealing tightly guarded details of the latest multimillion-dollar celebrity housing transactions, the gossipy anonymous blog has wreaked havoc among the city’s elite real estate agents and their wealthy clients. But who is behind the website, whose writer goes by such aliases as Yolanda Yakketyyak, the Real Estate Yenta and Donald Frump?”