The Applicability of Performance Studies to individuals

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Boyd Baumgartner
Posts: 567
Joined: Sat Aug 06, 2005 11:03 am

The Applicability of Performance Studies to individuals

Post by Boyd Baumgartner »

(article attached)
Group-to-individual-generalizability.pdf

https://www.studyfinds.org/study-finds- ... -mistakes/
BERKELEY, Calif. — People like to read studies. This, we at StudyFinds, know to be true. But we also know that people like to debate — and often debunk — the veracity and viability of studies, too. Now a study that actually studied studies seems to side with the naysayers, finding that research which evaluates large groups of people leads to skewed results. In order to get a better and more accurate grasp of mankind, the authors say, scientists need to study people individually.
Researchers from the University of California at Berkeley believe that big data can be a big mess, especially for health practitioners who depend on medical research to guide them in their practices. That’s because human beings can be so markedly different from one another, often-studied subjects like mental health and physiology can yield unreliable conclusions when coming from massive segments of a population.

In order to get a better and more accurate grasp of mankind, scientists need to conduct studies on people individually, not in large groups, a new study finds.

“Diseases, mental disorders, emotions, and behaviors are expressed within individual people, over time. A snapshot of many people at one moment in time can’t capture these phenomena,” argues study lead author Aaron Fisher, an assistant professor of psychology at the university, in a statement.

Fisher collaborated with scientists from Drexel University and the University of Groningen in the Netherlands to analyze data on hundreds of adults — some mentally or physically sound, others suffering from various conditions such as depression, anxiety, or post-traumatic stress disorder. Participants had completed surveys about their mental health and had their heart rates monitored via electrocardiogram.
Researchers used the data to conduct six different experiments. They sought to find out whether the conclusions of each study would successfully apply to participants individually.

One study that focused on how frequently depression sufferers reported feeling worried. Results tallied from the pool of participants showed that depressed people worry a significant amount. But when the analysis was applied individually, the results were all over the map. Some participants worried hardly at all, while others were notably beyond the group average.

Another experiment that centered around the link between fear and avoidance showed a strong correlation when measured as a group. Yet a significant number of participants who experienced fear had no issues with avoiding various activities.

Across all six experiments, the authors could not show that what was concluded for the group applied to most individuals.

“If you want to know what individuals feel or how they become sick, you have to conduct research on individuals, not on groups,” says Fisher, who argues that studies should simply be modified instead of completely ignored. “People shouldn’t necessarily lose faith in medical or social science. Instead, they should see the potential to conduct scientific studies as a part of routine care. This is how we can truly personalize medicine.”

The full study was published June 18, 2018 in the Proceedings of the National Academy of Sciences journal.
This phenomenon is not new. It falls under the umbrella of Generalizability. Here is a great paper that adequately frames and dives deep into the issue if that's your thing.
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Boyd Baumgartner
Posts: 567
Joined: Sat Aug 06, 2005 11:03 am

Re: The Applicability of Performance Studies to individuals

Post by Boyd Baumgartner »

So, what this means practically is this. People who are going to bring up the NAS report as having credence, must now contend with the fact that the NAS publishing arm also put forth a finding that is in direct opposition to the PCAST Report.

Specifically, this: (emphasis mine)
Finding 5: Latent fingerprint analysis

Foundational validity. Based largely on two recent appropriately designed black-box studies, PCAST finds that latent fingerprint analysis is a foundationally valid subjective methodology—albeit with a false positive rate that is substantial and is likely to be higher than expected by many jurors based on longstanding claims about the infallibility of fingerprint analysis.

Conclusions of a proposed identification may be scientifically valid, provided that they are accompanied by accurate information about limitations on the reliability of the conclusion—specifically, that (1) only two properly designed studies of the foundational validity and accuracy of latent fingerprint analysis have been conducted, (2) these studies found false positive rates that could be as high as 1 error in 306 cases in one study and 1 error in 18 cases in the other, and (3) because the examiners were aware they were being tested, the actual false positive rate in casework may be higher. At present, claims of higher accuracy are not warranted or scientifically justified. Additional black-box studies are needed to clarify the reliability of the method
Given that the abstract of the paper specifically describes the conditions for general to individual applicability to occur, it should be fun to bring this up in the next defense interview that tries to put up a cursory mention of PCAST.
Only for ergodic processes will inferences based on group-level data generalize to individual experience or behavior. Because human social and psychological processes typically have an individually variable and time-varying nature, they are unlikely to be ergodic.
In English, this just means that you can't stereotype individuals based upon aggregated data for people in that group. Given this day and age, I'd hope we wouldn't need a scientific journal to tell us that, but.....here we are. Error rate studies say zero about the case I'm working now.
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