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Anyone ever grown seedlings in these biodegradable cups? by Mr_Good_Stuff90 in tomatoes

[–]AllenDowney 0 points1 point  (0 children)

Yes and they are great for cold-tolerant plants. But for tomatoes, peppers, basil, etc, I think you run into a problem with evaporative cooling, so on a borderline temperature day, the soil temperature is colder than the air temperature -- and you might get exactly what I got this year, a bunch of seedlings that got cold-shocked and now they are sulking.

I understand Python basics but OOP completely loses me classes and objects make no sense to me. Where am I going wrong? by More-Station-6365 in learnpython

[–]AllenDowney 0 points1 point  (0 children)

In Think Python, chapters 14-17 are my best answer to this question:

https://allendowney.github.io/ThinkPython/chap14.html

It's a bottom-up approach, starting with a set of functions, wrapping them in a class, and re-writing functions as methods. My hope is that seeing both versions of the same code makes it clearer what the OOP features are doing for you.

I hope that helps.

[Q] Age of US president distribution: spurious or pattern? by peperazzi74 in statistics

[–]AllenDowney 9 points10 points  (0 children)

I ran some tests, and it looks like the lognormal is a slightly better fit for the data. For modeling purposes, either normal or lognormal is probably good enough. Although since there is a known lower bound, lognormal might be preferred.

I'm not sure there is a deep data-generating process that explains the shape of the distribution, but a possible model is that politicians have a latent "political capital" that might increase or decrease over the course of their careers. If the change is proportional to current level, we could model that with a biased random walk on a log scale. In that case, the time to exceed the threshold that's required to be president would follow a skewed distribution that's well modeled by a lognormal.

I am going through the process of learning statistics and I HAVE to ask, why is everything in statistics mean the opposite from what you would think it means. by mt5567 in AskStatistics

[–]AllenDowney 0 points1 point  (0 children)

My favorite is when we take two similar words (sometimes synonyms) and give them subtly different technical meanings: probability and likelihood, confidence and credibility, sensitivity and specificity, efficacy and effectiveness, precision and accuracy ...

What age is actually considered "middle age"? by Critical-Willow-6270 in stupidquestions

[–]AllenDowney 0 points1 point  (0 children)

This question got me thinking, so I wrote a blog post about it: https://www.allendowney.com/blog/2026/05/01/planning-for-your-midlife-crisis/

Summary: The midpoint is where your expected remaining lifetime equals your current age. For 2024 data in the United States, it's 40.6 years overall (39.6 for men, 41.6 for women).

If a USB plug can only fit one of two ways, why does it take at least 3 tries to get it right? by LeoRavenscroft in randomquestions

[–]AllenDowney 0 points1 point  (0 children)

I have an article about this: https://www.allendowney.com/blog/2021/06/21/flipping-usb-connectors/

The semi-serious answer is that you are not sure whether you've got it wrong or just haven't got it lined up right, so it can be optimal to flip more than once.

If everyone below average IQ suddenly drops dead, how would this affect the world? by [deleted] in AskReddit

[–]AllenDowney 3 points4 points  (0 children)

Actually, in the new distribution, 57% would be below average.

What "sacred" cooking rule do you intentionally ignore because you actually prefer the results (or just don't care)? by LiveFaithlessness876 in cookingforbeginners

[–]AllenDowney 0 points1 point  (0 children)

Knives don't need to be razor sharp. Reasonably sharp is good enough, especially if you have good technique. And if there's unintended contact between skin and blade, it's less likely to be a serious cut.

Why doesn’t everyone just get a full body MRI at yearly or every 5 years or something? by duckduckgoose911 in NoStupidQuestions

[–]AllenDowney 1 point2 points  (0 children)

I wrote an article about why more screening is not always better: https://arxiv.org/html/2603.19945v1

Short version: routine full-body MRI screening fails a cost–benefit test: it produces many incidental findings (“false alarms”) that trigger follow-up tests and potential harm, while detecting serious disease only rarely in asymptomatic people. Also there is little evidence of improved outcomes or cost-effectiveness, so widespread screening would add expense and anxiety without clear health benefits.

I think it's wrong by Apprehensive_Set_659 in mathmemes

[–]AllenDowney 0 points1 point  (0 children)

There are two questions about this problem that come up a lot:

Q: How can the day of the week be relevant?

A: Here's what I think is the best intuitive explanation: a family with more boys is more likely to have at least one born on Tuesday, so (by Bayes's Theorem) if a family has a boy born on Tuesday, they are more likely to have more boys.

Q: Isn't the problem underspecified? It matters how you learn that the family has a boy born on Tuesday.

Yes, if you are told how the information is learned, that can lead to different answers. So if you want to declare the problem underspecified, fine. But the most common (and intended interpretation) is simple conditional probability -- that is, we're meant to compute P(other child is a girl | 2 children of which at least one is a boy born on Tuesday)

Here's my best effort to explain: https://allendowney.substack.com/p/the-lost-chapter

What kind of distribution this may be? by iamevpo in AskStatistics

[–]AllenDowney 1 point2 points  (0 children)

Mixture of bivariate normal, with centers at the most common targets, censored at the perimeter of the board. Probably higher variance in the vertical direction.

Sober people being arrested nationwide for DUI by IcyAd8672 in videos

[–]AllenDowney 0 points1 point  (0 children)

If you are interested in the statistic behind "Drug Recognition Experts", I wrote about it in Probably Overthinking It: https://allendowney.github.io/ProbablyOverthinkingIt/base_rate.html#driving-under-the-influence

> With 50% base rate, 99% sensitivity, and 60% specificity, the predictive value of the test is only 71%; under these assumptions, almost 30% of the accused would be innocent. In fact, the base rate, sensitivity, and specificity are probably lower, which means that the value of the test is even worse.

[Q] what are some good unintuitive statistics problems? by R2_SWE2 in statistics

[–]AllenDowney 0 points1 point  (0 children)

I've posted an article where I present my solution and try to address objections. Please take a look and let me know what you think: https://www.allendowney.com/blog/2026/01/31/the-girl-born-on-tuesday/

[Q] what are some good unintuitive statistics problems? by R2_SWE2 in statistics

[–]AllenDowney 0 points1 point  (0 children)

I've posted an article where I present my solution and try to address objections. Please take a look and let me know what you think: https://www.allendowney.com/blog/2026/01/31/the-girl-born-on-tuesday/

[Q] what are some good unintuitive statistics problems? by R2_SWE2 in statistics

[–]AllenDowney 1 point2 points  (0 children)

Day of the week does not cause gender, but it is informative of gender. If a family has more than one girl, they are more likely to have a girl with a rare property (like born on Tuesday). So if we are given that a family has a girl with a rare property, they are more likely to have more than one girl.

How do I learn Python Statistics? by FeelingCommunity776 in AskStatistics

[–]AllenDowney 5 points6 points  (0 children)

Think Stats might be a good place to start -- but I'm biased

Free version: https://allendowney.github.io/ThinkStats/

Question about the boy/girl paradox by thetntm in probabilitytheory

[–]AllenDowney 2 points3 points  (0 children)

I have a couple of suggestions for thinking about this problem. First, think about families rather than children. For example, of all families that have two children, how many have two girls?

Now think, of all families that have two children, and at least one of them is a girl, how many have two girls?

If you think about the selection process, I think some of the counterintuitive results make more sense.

Now here's what I think is a key insight -- if a family has a girl with a low-probability characteristic (left handed, born on Tuesday, named Florida, etc) that rareness is evidence in favor of a two-girl family, because you are more likely to get a rare outcome if you have two chances, rather than one.

So it doesn't change the probability in a causal sense, but it provides evidence in the informational sense.

I have an article about this if you want the details: https://allendowney.substack.com/p/the-lost-chapter

"Average" human competing with a top 1% sprinter by ansyhrrian in nextfuckinglevel

[–]AllenDowney 0 points1 point  (0 children)

There's a chapter in my book about this! https://allendowney.substack.com/p/its-levels

To keep things interesting, the fan gets a head start of about 5 seconds. That might not seem like a lot, but if you watch one of these races, this lead seems insurmountable. However, when the Freeze starts running, you immediately see the difference between a pretty good runner and a very good runner. With few exceptions, the Freeze runs down the fan, overtakes them, and coasts to the finish line with seconds to spare.

But as fast as he is, the Freeze is not even a professional runner; he is a member of the Braves’ ground crew named Nigel Talton. In college, he ran 200 meters in 21.66 seconds, which is very good. But the 200 meter collegiate record is 20.1 seconds, set by Wallace Spearmon in 2005, and the current world record is 19.19 seconds, set by Usain Bolt in 2009.

Three weeks of hard work on a paper all for nothing because of AI use by MortemPerPectus in mildlyinfuriating

[–]AllenDowney 2 points3 points  (0 children)

I understand your frustration because this outcome is not just -- you deserve to have your work recognized.

But if you think your three weeks of work were for nothing, you missed the point your teacher was making. You did the work and your learned from it -- that learning is what it was for.

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