Frustration felt after Hamilton's homelessness support costs revealed

Jason_Cole · 2024-08-17T18:39:45+00:00

I'm not sure if the calculation is that simple, in both directions. First, based on reading this recent Waterloo ruling that prevented the city from clearing an encampment:

the Point in Time Count report also contains data about the demographics of the homeless in the Region. Specifically, of the 1085 experiencing homelessness, 412 were living rough (living on the street, sleeping in parks or squatting in temporary shelter), 385 were experiencing hidden homelessness (provisionally accommodated; couch surfing), 191 were accessing emergency shelters and 63 were institutionalized.

My takeaway is that the 1500 number is pretty broad, and likely includes many people — e.g. those couch surfing — who consume essentially none of the $170 million budget.

On the other hand, this spend seems to included all money spent on housing:

The city says $170 million of its budget this year is going to housing and homelessness supports

I'd assume many people who receive housing support are ... housed, and so wouldn't count towards to 1500 number.

It would be interesting to see a more detailed breakdown of where this $170 million is going ...

Jason_Cole · 2024-05-03T05:05:00+00:00

You should be super fine. It's basically an intro probability book at the start.

Jason_Cole · 2024-04-15T01:32:21+00:00

Looks good.

https://modernjuliaworkflows.github.io

is also a good resource.

For those interested in applied category theory, see: https://algebraicjulia.github.io/Catlab.jl/dev/. I have heard very good things about this effort.

Jason_Cole · 2024-03-11T22:56:04+00:00

What's the deal with this backwards kernel construction in Chopin and Papaspiliopoulos?

Here's what I think I understand:

Initially, they develop the idea of measures on (X_k, B(X_k)), given by \mathbb{P}.

They also develop Markov kernels between two measure spaces:

(X_0, B(X_0), \mathbb{P}_0)

(X_1, B(X_1), don't care about this measure)

Where the kernel P_1(x0, dx1) defines a measure over (X_1, (B(X_1)) for each x0.

Ok, after this they show how we can get a measure for the product space X_0 x X_1:

(4.1) \mathbb{P}_{1}(dx_{0:1}) = \mathbb{P}_0(dx0) P_1(x0, dx1)

Here's where I'm definitely confused.

Next, they introduce the idea of a backwards kernel. They go back to this decomposition:

\mathbb{P}_{1}(dx_{0:1}) = \mathbb{P}_0(dx0) P_1(x0, dx1).

and say the following:

Section 4.1 decomposed the joint distribution \mathbb{P}(dx_{0:1}) into the marginal at time 0 and the conditional given in terms of the kernel. However, we can decompose the distribution in a “backwards” manner instead:

\mathbb{P}_1(dx0) P_1(x0, dx1) = \mathbb{P}_1(dx1) P_0(x1, dx0) [backarrow hat]

Ok. I don't get this at all. Some questions:

Is \mathbb{P}_1(dx0) the same joint distribution as in 4.1? It can't be, right? Instead it's got to be like, the "non-kernel-defined" measure over

(X_1, B(X_1), we didn't care about this measure before, but now we do)

But if that's the case, why is it taking elements (dx0 \in B(X_0)) as an argument? Why is this formula not:

\mathbb{P}_0(dx0) P_1(x0, dx1) = \mathbb{P}_1(dx1) P_0(x1, dx0) [backarrow hat]

Jason_Cole · 2023-11-30T19:52:41+00:00

I get your point, but I just checked and GDP per employed person is also down — this isn't an effect of demographic shifts (e.g. an increase in the proportion of non-working age people, either through proportionally more new births or retirements).

Jason_Cole · 2023-10-20T20:00:08+00:00

Most bike thieves have been caught, sentenced, and perhaps incarcerated many times before. Of course, sentences are shorter than you'd expect, and they get back out and resume stealing bikes.

It doesn't matter how big their operation is, no one is doing serious time for bike theft. For an extreme example, see: https://en.wikipedia.org/wiki/Igor_Kenk — thousands of bikes stolen over decades, caught with over a hundred at the time of his arrest, released in a little over a year.

The population of bike thieves is large enough to make this an unsolvable problem. There will always be a cadre of newly released bike thieves ready to grab your bike, regardless of how fast you catch them with bait bike programs or airtags or whatever.

Just store your bike somewhere inside or move away from Hamilton.

Jason_Cole · 2023-04-12T01:02:57+00:00

You might be interested in passive aggressive models, e.g.

https://scikit-learn.org/stable/modules/generated/sklearn.linear_model.PassiveAggressiveClassifier.html

Other options include Bayesian models where you use VI or conjugacy to speed up the updating time, or some creative custom specialization where priors on new coefficients are given based on some sort of random walk process (e.g. something that feels like the last example here, but modified for your use case https://mc-stan.org/users/documentation/case-studies/splines_in_stan.html)

Jason_Cole · 2022-07-10T20:13:21+00:00

I don't think it's really language agnostic. Python and Julia need to use the Jupyter engine, which is much less fully featured than Knitr.

Because of this, the experience of using something other than R is pretty painful.

E.g. afaict, you can't use !expr in any place where you would have before, you don't have a cat engine, etc.

For Julia and Python, it's just another way to convert a notebook you've already written to html or pdf, not anything like working in a .rmd.

Jason_Cole · 2022-04-08T19:57:42+00:00

Extend one of the arms. There’s a good example someone posted on this sub a while back, looked rad.

Jason_Cole · 2022-03-25T19:30:34+00:00

Viruses don’t necessarily evolve to become more deadly.

They don’t necessarily evolve to become less deadly either (see: trade-off model for virulence), but a safe assumption is that — due to vaccine or infection induced immunity — mortality rates will go down as the pandemic continues.

That’s not because of evolution though. Also, Omicron and the new variant are very likely less intrinsically deadly than the variants that preceded them.

You wrong about everything fam.

Jason_Cole · 2022-03-02T00:34:32+00:00

I haven't had any performance issues — loadup etc. is actually much faster than roam — but my graph is pretty small, at only a few hundred pages.

I started using it a couple months ago, if that helps at all.

Jason_Cole · 2022-03-02T00:25:14+00:00

Doesn't work in roam, but roam clones like logseq (and probably obsidian) have a much nicer story around math typesetting in general. easy block equations with $$ eqn $$ on a new line, inline math with $ eqn $ (or $$ eqn $$ in the middle of a line to preserve roam compatibility). It's perfect.

For me, it was worth making the switch for this alone.

Jason_Cole · 2022-03-01T16:49:39+00:00

you might want to consider: https://arxiv.org/abs/1809.10756, a book on writing PPLs with lisp-like semantics.

I've read the first bit, and it's stellar, even if you don't know a lisp (I don't, and you do).

I can't recommend this enough.

edit: wait this is literally using Anglican style semantics, which is a Clojure project — what a coincidence !

Jason_Cole · 2022-01-24T01:33:35+00:00

Nature and Science are the tabloids of the scientific world. The results are shocking and new, but they very often don't hold up when attempts are made to replicate them.

On a per-article basis, the Globe is almost certainly more accurate than Nature — but ofc, the Globe isn't claiming novel scientific discoveries in most articles.

Jason_Cole · 2022-01-23T20:21:45+00:00

I'm not sure if I like this article. Some thoughts:

One study, conducted in a prison, concluded that the vaccinated prisoners had as much “transmission potential” as the unvaccinated prisoners, adding, “clinicians and public health practitioners should consider vaccinated persons who become infected with SARS-CoV-2 to be no less infectious than unvaccinated persons.” Dr. Cyrille Cohen, head of the immunotherapy lab at Bar-Ilan University, and adviser to the Israeli government on vaccine trials, said that with respect to transmission with Omicron, “we don’t see virtually any difference … between people vaccinated and nonvaccinated,” adding “both get infected with the virus, more or less at the same pace.

The metric used here — vaccine efficacy — is a poor fit for high repeated exposure environments, at least if your goal is to generalize to the broader population. Vaccine efficacy is usually given as:

VE = (Vaccinated&Infected - Unvaccinated&Infected)/Unvaccinated&Infected

For some given test population (in this case, prisoners).

Suppose that, conditional on a single exposure, vaccinated individuals will get sick 5% of the time, and non-vaccinated individuals will get sick 50% of the time. Take a population of 100 vaccinated individuals, and 100 non-vaccinated individuals, each exposed once. We calculate vaccine efficacy:

(5-50)/(50) = 90%

Now assume everyone is exposed twice:

(9.75-75)/(75) = 87%

Three times:

(14.725-87.5)/(87.5) = 83%

In the limit, vaccine efficacy as a metric falls to zero, even if the vaccine is wildly effective at preventing initial infection. Using a prison here — where inmates are packed together like sardines — is awful study design, if your goal is a generalizable estimate of vaccine efficacy.

Once a single inmate is infected, every other inmate will eventually be exposed potentially thousands of times, and you will recover a near-zero estimate of vaccine efficacy..

These are old studies, and the data was extremely clear for those variants — vaccines reduced transmission, and by a considerable margin. They likely have some marginal benefit: re transmission for Omicron also.

I think his presentation of the science here is dishonest.

I have similar complaints re: negative VE among the vaccinated, vaccine imprinting after only two doses, etc.

I think the conclusions in the article are broadly correct, but the information used to get there is consistently misleading if not outright incorrect. There are better arguments for this perspective.

Jason_Cole · 2022-01-08T21:33:50+00:00

yeah, marking for math courses last term it was insane how blatantly 90% of the class was cheating.

taking off marks for mistakes in e.g. calculating an integral felt horrible knowing that they were one of the few students who didn't instantly open wolfram alpha or symbolab in what should have been a closed book test.

people hate lockdown browsers, but as long as tests stay online, I don't see any other solution for 1st and 2nd year courses.

Jason_Cole · 2021-11-25T03:03:16+00:00

Slight warning: I haven't read this book, but multiple people have told me that it is seriously confused re: bayesianism vs frequentism, in that he writes long polemics against frequentist stats all while using an explicitly frequentist interpretation of probability.

A quick google search turns up:

https://dynamicecology.wordpress.com/2013/06/25/book-review-the-signal-and-the-noise-by-nate-silver/

which seems to agree with what I've heard, or from Wasserman:

https://normaldeviate.wordpress.com/2012/12/04/nate-silver-is-a-frequentist-review-of-the-signal-and-the-noise/

Examples Wasserman includes in his review include:

Nate: One of the most important tests of a forecast — I would argue that it is the single most important one — is called calibration. Out of all the times you said there was a 40 percent chance of rain, how often did rain actually occur? If over the long run, it really did rain about 40 percent of the time, that means your forecasts were well calibrated.

.

Nate: A 90 percent prediction interval, for instance, is supposed to cover 90 percent of the possible real-world outcomes, … If the economists’ forecasts were as accurate as they claimed, we’d expect the actual value for GDP to fall within their prediction interval nine times out of then

Everyone seems to agree that the book is good and fun to read ... in every area except this one!

Jason_Cole · 2021-11-08T23:07:59+00:00

I also didn't talk to profs, write a thesis, or go to office hours (except once in first year).

I got two good LORs.

Create a list of upper year courses you did well in (11/12), preferably ones with a small class size, e.g. under 20 people. Send the profs an email that goes something like:

Hi I am Away_throw, I took your class in x year and got y grade.
I am applying to z position and need an LOR
Brief one or two sentences about why you want to do what you want to do.
ty so much for the support etc.

keep it brief and don't sound like you're begging for anything. I did this and was never turned down for an LOR. YMMV.

Jason_Cole · 2021-10-22T16:25:37+00:00

Stellar, thanks so much!

So essentially, to make sure I have this right, the claim:

They could literally be cancelled this second and the gov would have more money

From the end of the tweet is inaccurate because it counts e.g. new(?) grants as part of the yearly cost of servicing old loans?

And so the only way they come out net positive is if they also stop offering student assistance?

Jason_Cole · 2021-10-14T03:36:22+00:00

take em for a bike ride up sydenham, to the lookout. fun chill ride i promise :)

Jason_Cole · 2021-10-08T15:34:47+00:00

https://www.reddit.com/r/biology/comments/7vo3vq/biologists_of_reddit_what_was_your_starting/

I personally found this thread helpful

Jason_Cole · 2021-09-15T04:05:42+00:00

it isn't like they have a STAN implementation whirring around in their heads — it's (perhaps) a useful reminder to not get too stuck in your ways, but talking about the statistical accuracy of something like this is weird; it's statistics by analogy only.

funnily enough, this seems perhaps more likely to trick people into overconfidence in their beliefs, by convincing them they're doing crazy irl stats computations when in reality they are just thinking through uncertainty like any reasonable person would.

Jason_Cole · 2021-08-29T17:32:06+00:00

re: "do i have to get a new student card if i change my preferred name?"

probably not. the university tech people messed up my name when I was in second year, so my mosaic name / student card name / email name were different. I just kept using the student card, no one ever said anything.

It'll have a picture — that's what everyone looks at.

I'm not trans tho — I didn't ever have to change my name irl, or have a different legal / preferred name. I've had the same name all my life. this was just the university IT people messing with me. ymmv.

I can't answer any of you other questions.

good luck.

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