[[bitcoin]] was suppose to be a steady form of asset that resists broader economic trends, but so far it has been a speculative tech investment
in 2022, it has closely mirrored the NASDAQ movements
#til2022 Sahara Desert Circles
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💁♂️: Circle markings in the Sahara Desert in Algeria. Could be a result of seismic surveys used for natural gas extraction
🤔:
#data-science Spatio-Temporal Extreme Event Modelling of Terror Insurgencies
Authors: Lekha Patel
Highly unpredictable but high impact outcome events are important to predict accurately
Arbitrary space-time region
Inhomogeneous baseline intensity
Self-exciting marked spatio-temporal model
Triggering intensity is modelled with Gaussian Process prior distribution to flexibly capture intricate spatio-temporal dependencies between an arbitrary event and previous events
Novel generalized zipf distribution to measure the intensity of the event
customized Markov chain Monte Carlo method to estimate the model parameters
Extreme value analysis focuses on the characterization of events that lies at the tails of a distribution
i.e. earthquakes, hurricanes, flooding, wildfires
Two common approaches from statistical point of view
calculating a sequence of maximum (minimum) values over blocks of data and fitting these values to their large sample distribution (the Generalized extreme value distribution)
find observations that exceeds (fall below) a given threshold and fits the Generalized pareto distribution to these exceedance values (Peaks over Threshold method (PoT))
A novel approach is to use point process modelling
Used to probabilstically describe an event that happens in space-time
Homogeneous point process can be used if the event occurs in a constant rate
Self-exciting processes can be used to capture dependencies that naturally arise in events that may have connections
To measure the different impact of these events, layered a mixture model to estimate the discrete mark of the event
Marks above a threshold can be modelled with a Generalized-Zipf distribution
==It is similar to a two-hurdle model except the first hurdle is the self-exciting point process and the second hurdle is a generalized zipf model==