Archive for Pacific North West

asymptotics of M³C²L

Posted in Statistics with tags , , , , , , , on August 19, 2018 by xi'an
In a recent arXival, Blazej Miasojedow, Wojciech Niemiro and Wojciech Rejchel establish the convergence of a maximum likelihood estimator based on an MCMC approximation of the likelihood function. As in intractable normalising constants. The main result in the paper is a Central Limit theorem for the M³C²L estimator that incorporates an additional asymptotic variance term for the Monte Carlo error. Where both the sample size n and the number m of simulations go to infinity. Independently so. However, I do not fully perceive the relevance of using an MCMC chain to target an importance function [which is used in the approximation of the normalising constant or otherwise for the intractable likelihood], relative to picking an importance function h(.) that can be directly simulated.


Posted in pictures, Travel, Wines with tags , , , , , , , on December 20, 2015 by xi'an

"another local red wine with a strong personality, Seattle, Aug. 10, 2015""more details...

forest fires

Posted in Mountains, pictures, Travel with tags , , , , , , , , , , , , , , on August 26, 2015 by xi'an

fire1Wildfires rage through the US West, with currently 33 going in the Pacific Northwest, 29 in Northern California, and 18 in the northern Rockies, with more surface burned so far this year than in any of the past ten years. Drought, hot weather, high lightning frequency, and a shortage of firefighters across the US all are contributing factors…fire2Washington State is particularly stricken and when we drove to the North Cascades from Mt. Rainier, we came across at least two fires, one near Twisp and the other one around Chelan… The visibility was quite poor, due to the amount of smoke, and, while the road was open, we saw many burned areas with residual fumaroles and even a minor bush fire that was apparently let to die out by itself. The numerous orchards around had been spared, presumably thanks to their irrigation system.fire3The owner of a small café and fruit stand on Highway 20 told us about her employee, who had taken the day off to protect her home, near Chelane, that had already burned down last year. Among 300 or so houses. Later on our drive north, the air cleared up, but we saw many instances of past fires, like the one below near Hart’s Pass, which occurred in 2003 and has not yet reached regeneration. Wildfires have always been a reality in this area, witness the first US smokejumpers being based (in 1939) at Winthrop, in the Methow valley, but this does not make it less of an objective danger. (Which made me somewhat worried as we were staying in a remote wooden area with no Internet or phone coverage to hear about evacuation orders. And a single evacuation route through a forest…)fire5Even when crossing the fabulous North Cascades Highway to the West and Seattle-Tacoma airport, we saw further smoke clouds, like this one near Goodall, after Lake Ross, with closed side roads and campgrounds.fire4And, when flying back on Wednesday, along the Canadian border, more fire fronts and smoke clouds were visible from the plane. Little did we know then that the town of Winthrop, near which we stayed, was being evacuated at the time, that the North Cascades Highway was about to be closed, and that three firefighters had died in nearby Twisp… Kudos to all firefighters involved in those wildfires! (And close call for us as we would still be “stuck” there!)fire6

hiking the Dungeness spit

Posted in Mountains, pictures, Travel with tags , , , , , , , , , , , on August 16, 2015 by xi'an

sandspitsandspit2We had a great hike while staying on the Olympic peninsula, walking a sand spit housing the Dungeness National Wildlife Refuge, located at the end of the Puget Sound and the Strait of Juan de Fuca. The sand spit goes into sea for five and a half miles, enlighthusding up at a decommissioned lighthouse that has been preserved by a local association, with voluntary keepers staying there one week at a time. Which is a great way to spend a retreat far from the maddening crowd… Except for the few hikers managing the walk to the lighthouse, of course!

The walk is quite easy, on packed sand, provided there is no high tide at the time, and few enough people embark on the eleven miles trip to make it quiet and peaceful. It is a wee bit monotonous, obviously, even though watching for birds and flotsam and jetsam enlivens the trip. Nothing extreme, obviously, but great views on the Olympic National Park peaks. With a cooling wind that hid the strength of the sun. As we discovered too late!

While there are many potential species of birds taking refuge on that preserved spit, we did not see many. Besides the obvious gulls and relatives, a heron, two types of sandpipers, and a loon-like bird at sea. Plus a few seals fishing at sea, clearly not bothered by the potential orcas around the spit. That we sadly did not see.


another Olympian sunrise

Posted in Mountains, pictures, Running, Travel with tags , , , , , on August 10, 2015 by xi'an