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One thing I love about is that you always new things, even when giving a lecture about stuff that you know (or you think you do) very well.

Today a student asked why we should use Student's -test at all when comparing samples with equal variances if you can use Welch's variant, which works with unequal variances... that is, why bother checking equality of variances?

Indeed, in the case of equal variances the calculated t statistics would be the same!

This led to a great discussion involving 3 instructors, a bunch of students, and a few simulations in which I really enjoyed!

The answer is that Welch's variation also changes how degrees of freedom are calculated, so no they are not equal!

Also, the current recommendation is NOT to check for variance equality (e.g. using Levene's test) as this paper clearly points out, lest you want to increase your Type I error!


Gotta go change some slides...

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"We have documented more than 200 relative values of gold and silver across almost 3000 years (2500 bce–400 ce) to establish value benchmarks for essentially pure metal. Our aim is to improve understanding of ancient economies by enabling regional and temporal comparisons of these relative values."

Ross, J., & Bettenay, L. (2023). Gold and Silver: Relative Values in the Ancient Past. Cambridge Archaeological Journal, 1-18. doi: @econhist @archaeodons @antiquidons

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Babies only take 9 month to make .. try writing a thesis😅

@OpenAcademics @AcademicChatter

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Manufacturers of all kinds bootstrap the DMCA into a new doctrine that Jay Freeman calls "felony contempt of business model." Removing DRM is illegal, so any business model that hides behind DRM is illegal to thwart. (via @pluralistic)

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The LI-900 silica tiles used on the Space Shuttle were such poor heat conductors you could grab them with bare hands seconds after pulling them from a 2200 degree oven.

#nasa #science #tech #space

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This is the final stage of tetanus when the nerves fire continuously and the body contorts into an agonizing posture known as opisthotonus. In addition, the mastication muscles clamp down to form the hallmark of the disease, lockjaw. An unnerving and unintentional grin that exposes the teeth, known as risus sardonicus, also appears as a result from contracted facial muscles.

This 19th-century painting by the surgeon Charles Bell now hangs in @surgeonshall in Edinburgh. #histmed #MedMastodon

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"Is there a doctor on the plane?"✈️

This JAMA article has printable cards that can remind you what to do in a medical emergency on an airplane.

In-Flight Medical Emergencies: A Review

#MedMastodon #safety #doctor #physician

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Possibly the most frightening talent of the brown bear is an uncanny ability to blend seamlessly into the environment in an almost chameleon-like manner, allowing them to easily surprise their unsuspecting prey.

If you ever wonder if you are in the right workplace / have a good employer just call in sick. The answers you will get can be very informative.

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✅ And.... we're online!!! Check our review paper 📙 about physical activity🏃 in systemic #lupus in
@seminarthrheum ⬇️ This will inform the taskforce 🧑‍🎓 we are starting about PA in #SLE 👍

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A battery filled with algae is somehow managing to power this computer for months:

No-one's quite sure what's going on. Possibly the algae is serving as the medium catalyzing the interaction between the anode and cathode in the battery.

Except research shows the anode isn't degrading, which suggests ...

... the *algae* is producing the electrons.

Some thoughts on this in my blog post here, item 6:

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The face of CPR doll "Resuscitation Annie" is based off a death mask of a woman who drowned in Paris in the 1880s. The pathologist on duty became entranced by the girl with the enigmatic half-smile, and so he commissioned a plaster cast made of her face. She became known as "L'Inconnue de la Seine,” or “The Unknown Woman of the Seine.”

In 1955, a toymaker named Asmund Laerdal created what we now know as the CPR doll and based the face off this mask. #histmed #MedMastodon #histodons

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I very recently learned that the term “boycott” comes from someone’s actual name: Charles Boycott. Boycott was an English land agent who tried, in 1880, to collect unpayable rents from Irish peasants on behalf of an English aristocrat landlord. When he failed to collect the rents, he tried evicting the tenants. The Irish Land League responded with a campaign to ignore Boycott’s orders and isolate him socially and economically.

They not only ignored his eviction orders and threw manure at his process servers, but refused to deliver his mail or sell him food.

It was pretty effective—the British government eventually had to deploy a thousand soldiers (naturally, because the state works for the propertied class and none more than the 19th century British state) at a cost of some £10,000 to harvest £500 worth of crops. Boycott had to be evacuated by the soldiers, who even had to drive him out, as no locals would agree to drive his carriage out of the region.

Imagine being cancelled so hard that your name becomes permanently associated with getting cancelled.

For those of you who have just joined , especially if part of the , I found these two articles on getting started really informative.
The GitHub page from Joyeusenoelle had some interesting info I did not know (and I am a veteran of 3 weeks on Mastodon! 😂 )

Article from Wired's Justin Pot ( and FAQ from Joyeusenoelle on GitHub (

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