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Carnegie Mellon class of 2022.

These days, anyone can prop up an argument by pulling up a statistic. Much has been written about how statistics can be faulty — perhaps due to publication bias, or lack of generalizability, or researcher data-dredging.

But even genuine, trustworthy statistics, when plucked out of context, can mislead. Here are three common ways.

1. Using measures of the wrong thing

Does this tell us how marijuana usage has changed? (Source: ACLU Washington)

Say we want to know how rates of marijuana usage have changed over time in the U.S. The evidence: a graph of the yearly marijuana possession arrest rates.

The problem with this is quite clear: most marijuana users don’t get arrested! Maybe the change in marijuana arrest…


Is it really science of the brain, or just redundant psychology?

“When you cut your finger, there is a local release of prostaglandins and bradykinin. These bind to a nociceptor so it can become depolarized and send an action potential to the spinal cord where the signal can ultimately be transmitted to the brain. The activated nociceptor also releases Substance P to mast cells, which release histamine onto the nociceptor. This serves as positive feedback to keep it depolarized; the increased firing rate amplifies the pain response.”

What that paragraph says is all true. …


Do you think they haven’t heard from the “experts”?

via Adobe Stock

Not too long ago, “anti-vaxxers” were just a ridiculed fringe group. Taking shots for polio and the measles and such seemed like an ordinary part of life. Why would anyone see a problem with it?

But now that the COVID-19 vaccine has entered the scene, people are feeling pressured. They’re questioning whether this coerced intervention is really going to be worth it, often with the same concerns that vaccine critics have pointed out for years.

The experts have noticed this phenomenon they call vaccine hesitancy. The response: insisting that the COVID-19 vaccine is effective, and that we need to take…


“Bias” and “lurking variables” are two of the most important factors in judging how well a study is designed. And from my experience as an introductory statistics TA, they’re the two concepts that get most often mixed up!

With Bias, You Can’t Claim a Result Applies to the Broader Population

Sometimes statistics “miss the mark” — they’re off from the true figure. (Image by Lucian Alexandru Motoc, via Dreamstime)

When you try to get a figure for a population (say, an average, or a percentage, or the strength of a correlation), but you can’t gather information from every member, you can select a representative sample and get the statistic from that. There’s bound to be some variation, of course. It’s not going to be exactly the same figure as for the…


Feodora Chiosea via Dreamstime

Try reading the following list, then covering it up and seeing how many you can remember: XCN, NPH, DFB, ICI, AES, PNX. How did you do? Most people would start to falter at the third chunk of letters, if not sooner.

Now, try doing the same for this list: X, CNN, PHD, FBI, CIA, ESPN, X. You’d probably get more chunks correct. But these are the same letters! The only difference is the spacing; now you can see chunks that are familiar to you [1].

This illustrates the relationship between working memory and long-term memory. You can hold more in…


Having six fingers is a dominant trait! This fun fact leaves some people puzzled — that means if you have it, your kids will have it, right? Shouldn’t it be more common in the population than having five fingers, then? Does this mean it’s somehow advantageous to have an extra finger?

I’ve heard all these asked, and the answers are no, no, and no. Clearly, while many of us have heard the terms “dominant” and “recessive,” there’s not much clarity about what they mean. This article serves as a review.

Simple Dominance

In classical genetics, traits —passed-down physical characteristics — are encoded…


Schools don’t teach what we’ve already evolved to learn.

@gorodenkoff, via iStock

Reading, writing, mathematics, science, history — there’s a fairly narrow set of subjects considered “academic.” But not everyone needs these to succeed in adult life. Shouldn’t we be taught skills that are more broadly useful, like how to socialize with others, or how to be a problem solver?

And if people do want to learn those “academic” subjects, can’t they just learn naturally? …


Experts won’t address alternative COVID-19 theories? Fine, I’ll do it.

What if viruses don’t actually cause diseases? That’s the premise of The Contagion Myth, a recent book from the Weston Price Foundation gaining support among COVID-19 lockdown critics — surely there’s no reason to keep us spaced apart with cloth on our faces if this new disease is something like cancer or scurvy, not something that can be spread person-to-person.

How intriguing! This book gave me much to think about. But ultimately, while it does call attention to important health findings, it fails to do what its supporters claim: debunk germ theory.

The Argument

The authors explain terrain theory, the rival to…


Source: IoginovVados, via Depositphotos

“Look on the bright side.” “Mistakes help you learn.” “At least you tried.”

People offer these sayings with good intent. But they may not be the most helpful when you’re grieving a genuine disappointment. At this point, they’re like saying “Everything happens for a reason” at a funeral: not a meaningful contribution, and probably not a welcome one.

It’s okay to view a failure as something tragic, something that should not have happened. You don’t have to spin it into some destined blessing. Still, a realistic reframe can help you feel better — and moving forward, do better. …

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