The study did examine economic difficulty. "The authors find no evidence that trends in young adults’ economic circumstances, internet use, or television watching explain the recent decline in casual sexual activity."

If they find no relationship between changing economic circumstances and the outcome, and but a positive relationship between likelihood of co-residence with parents and the outcome, the likelihood that they have made statistical blunders greatly outweighs the likelihood that changing economic circumstances do not play a role.

Or, maybe poor people have about as much sex as rich ones when both live with parents.

When looking at any one variable they’re controlling for the others.

Living with your parents and facing economic difficulty are going to be correlated. If they're included together in a multivariable regression (which is often what people mean when they say "controlling for") then they're going to have multicollinearity and it's not possible to disambiguate the unique role of one versus the other.

It's plausible that the former variable is "stealing" some of the statistical significance of the latter, leaving the researchers with the impression that the latter is irrelevant.

Is that a statistical blunder? If economic circumstances provide no additional explanatory power beyond coresidence...

It is, because another way of phrasing that is "coresidence provides no additional explanatory power beyond economic circumstances."

When that's what your data looks like, proper study design either involves testing that hypothesis, or staying the fuck away from making conclusions that take one of those as significant and one as non-significant.

Not really, it's normal.

If you have two independent variables that are highly correlated, and you include both into the model, it's going to be pretty arbitrary which one ends up with statistical significance.

If we're dealing with weak effects and small data, there's very little one can do. That's why epidemiological studies like this kinda suck.

Controlling for confounders is better than not; it's also far short of adequate ("controlling" means "reducing a little," not "eliminating"), and in collinear variables you can easily kill the significance of one by adjusting for the other, if you're not careful (ordinarily we experiment with the order of controlling in a multiple regression, to see if that occurs, as well as testing for interaction effects.)

Great point. A percentage of those playing video games in their parents' basement would gladly be out traveling Europe or learning social skills at a state college - they just can't afford it.

> the growing percentage who coreside with their parents all contribute significantly to the decline in casual sex

> find no evidence that trends in young adults’ economic circumstances

I... uh... can’t make sense of these two statements together, both of which seem quoted from the paper.

You would have to dig into the paper to find out what exactly that means.

It might be that society is changing as a whole, and that individual variations of internet use don't contain any relevant information.

One of the cited works [0] did look at the relationship between mental health and sexual activity, if you're interested.

They found that higher sexual activity correlated with greater levels of depression, especially in men. Sexually active women also correlated with decreases in mental health, but the authors' interpretation was that that decline primarily stems from higher rates of victimization among that population, which would obviously lead to negative mental outcomes.

[0]: https://link.springer.com/content/pdf/10.1007/s10508-019-014...

Well perhaps reality doesn’t agree with your assumptions?

The study talks about how more young people are residing with their parents because of economic difficulty, but I'm not sure that's necessarily a major factor in the decline. Many people become sexually active before they move out of their parents' houses, and although it might be more challenging to find a private space, where there's a will, there's a way. Teenagers have been sneaking around to fool around for generations, and I don't think teenagers and young people of today are any less adept at finding a way to shack up if they're sufficiently determined.

So I think the focus is about what forces were not present in previous generations, and the Internet is certainly the most conspicuous factor. I'm not saying it's the decisive factor, but I'm not surprised it's a prime culprit.

The real earning power of minimum wage (aka, the standard teenage job) has declined by, what, 70% since the 70s? If it's more expensive, in real terms, to have a car, to rent a hotel room, to go out, then yes, it's going to be more difficult to get laid.

You can have sex while living with your parents, no car or hotel rooms needed. Not having money to go out might be a problem to meet people, true.

Note that in many countries, teenagers owning cars (and related activities) are not as prevalent as in the US. When I was a teenager, almost nobody I knew owned a car, and we all used public transportation, so there was no (dating) car culture around this.

There is a difference between “you can” and “you will bother to when there are plenty of easier and equally enjoyable things to do.”

I know I did bother. Sex is very interesting when you're a teenager.

Like I said, other countries don't have the same car-centric culture of the US. We've been managing to successfully have sex -- and find sex interesting -- without such an early access to cars!

The argument is not that it is impossible to have sex when you live with parents. It is that you are less likely to have casual sex if you live with them.

Where you would have had it, if you lived alone, you wont bother overcoming the "more challenging to find a private space" situation.

> I'm quite surprised to see that the leading theories in many of these studies revolve around competing forms of entertainment.

Really? If there's anything Game of Thrones kept reminding us of, its that males find defeating/killing other men in battle (and the "in battle" part is important, human warfare is very ritualistic just like Chimpanzee warfare) and fucking women equivocal if not related activities. Our ape brains don't appear to make much difference between virtual and physical, at least not enough to make one a lot less addictive than the other.

This study does not address hormonal changes, but I'd like to see the secular testosterone decline studied. Testosterone directly mediates sexual desire, so that should play a role.

You can want to have sex, but not have an available partner.

I think this is the reason too. There could be many possible reasons why young men have less testosterone than their ancenstors. Maybe the high child obesity rates? Chemicals in foods?

The high obesity rate is both caused and causing the lower testosterone. Endocrine disruptors (estrogen-like chemicals everywhere, not just in foods, originating from plastic manufacture, among others) are the biggest suspect IMO. They're probably causing both obesity and testosterone decline. It's an emerging topic of research with growing evidence.

I think in a century we're going to be looked upon as barbarians by our ancestors for some of the things we did to our bodies, just as we look upon the earlier generations who leaded gasoline, or smoked pervasively.

There’s a joke here in South America when you see a family walking around with many children....”no television”

Boredom leads to sex. From that, it stands to reason that less boredom leads to less sex. And entertainment is a way to reduce boredom.