Preview of 2021 YRBS Results

 

Preview of 2021 YRBS Results

The CDC released Youth Risk Behavior Survey Data Summary & Trends Report: 2011-2021 that contains crucial information about many of the 2021 YRBS results before the official release of such data (this will come a few months later).

Some words of caution regarding the CDC publication:

1) The 2021 YRBS was administered in the fall instead of spring, which raises the issue of comparability with previous results (at least for some survey items).

2) School closures may have affected responses to certain YRBS questions about school experiences during  "the past 12 months" -- such as being bullied in school. 

3) Results are given only in whole percentages without any further statistical information (such as standard error or confidence intervals).

4) Some results are inexplicably missing (such as the prevalence of fighting). 

Most results mentioned in the Summary are within a few percentage points of the previous 2019 YRBS results, and with the rounding and the absence of further statistical info it is difficult to decide if some of these represent  statistically significant relative changes.

For this reason we will address here only changes where the difference is at least 5 percentage points.

Sexual activities declined rapidly, similarly to the large drops in 2015:

The use of alcohol and marijuana also declined greatly; for alcohol this was an acceleration of a long-term trend but for marijuana this was a notable break with a long period of stability:

Any fears that a large portion of teens will turn to pot and alcohol out of boredom during long lockdowns and so become dependent can be put to rest in view of the 2021 YRBS results.

Prevalence of abuse and violence remained similar to 2019 except for bullying in school:

Since the YRBS bullying question asks about "the past 12 months" the prevalence rate may have been affected by lesser time spent in school. Furthermore, the switch of the test administration from spring to fall may also have had an influence on the results. For the above reasons I would recommend caution before jumping to the conclusion that kids have become less likely to bully each other.

Finally, the 2021 mental health results continued the trends set in 2019, namely a large increase in prolonged sadness and a slight increase in suicidal ideation: 

Note that the increase in the prevalence of sadness was not greater in 2021 than in 2019, be this measured in absolute (p.p) or relative (%) terms.

Summary

Judging by this CDC release, the most important 2021 YRBS results -- and especially those related to mental health -- could have been easily predicted in 2019 without us having any idea that a pandemic will drastically affect the lives of teens in 2020.

Notes:

We must keep in mind that much of the 2021 results were not yet released, and that what is important is of course a subjective matter.

The chapters on "Violence" and "Substance Use" in the CDC preview of 2021 YRBS results actually omit the vast majority of items dealing with these subjects -- for example numerous questions about hard drugs as well as various items related to tobacco or two items about fighting as well as two items about dating violence. If CDC selected, say, 2 out of 10 YRBS violence questions because only these two showed any increases then this would have severely mislead the press and could be a troubling example of institutional manipulation of the public.

WARNING:

The CDC asserts in their CDC Newsroom Releases that

1 in 5 (18%) experienced sexual violence in the past year—up 20% since 2017, when CDC started monitoring this measure.

More than 1 in 10 (14%) had ever been forced to have sex—up 27% since 2019 and the first increase since CDC began monitoring this measure.

It seems the 20% and 27% figures were calculated from data rounded to whole numbers!  

This is highly irregular, to put it kindly.

A change from "15" to "18" could be actually a change from 15.4 to 17.5, that is less than a 15% rise, not a 20% rise. The 27% rise could be in reality a 17% rise.

For CDC to be telling journalists that reports of sexual abuse increased by 27% without giving them even a hint that the actual figure may have been 17% is misleading and irresponsible.

Furthermore, for the CDC not to include any warning whatsoever that these large relative increases may be the result of random sampling rather than correspond to real changes in sexual violence is irresponsible.

CDC, YRBS, and Rape: The forced sex response has varied from 10 to 12 percent for girls and 3 to 6 percent for boys during the last two decades. It always struck me as strange that little attention has been paid to these statistics by the media and by the academia (at least when compared to attention and research dedicated to bullying issues) -- and, until now, by the CDC itself in its presentations of YRBS results.

If the current emphasis by the CDC on the YRBS sexual abuse items is an atonement for two decades of previous neglect, then I welcome the effort. Bad science, however, will only hurt such effort in the long run, even if it may seem that the means justify the ends (greater and more sensational news media coverage) in the short term.