His / Her face may be swollen due to subclinical hypothyroidism

https://www.nytimes.com/2017/10/09/science/stanford-sexual-orientation-study.html
https://ww2.kqed.org/futureofyou/2017/09/13/can-facial-recognition-detect-sexual-orientation-controversial-stanford-study-now-under-ethical-review/



Images/photos used in the samples do not take into account:
* Normally cycling women versus women using hormonal contraceptive methods.
"Ovulatory cycle and changes in face width: How women can tell when other females are ovulating using clues in their face - and how they may then try to hide their partners from the 'threat' of these fertile ladies (Women's attractiveness changes with estradiol and progesterone across the ovulatory cycle)"
* Her face may be swollen by a pregnancy.
* His / Her face may be swollen due to subclinical hypothyroidism.
* Persons with facial surgery or even worse Photoshopped / altered / retouched images (nose, lips, eyebrows) can introduce bias in the algorithm.

Also from the original research:
(208) Facial images. We obtained facial images from public profiles posted on a U.S. dating
(209) website. We recorded 130,741 images of 36,630 men and 170,360 images of 38,593 women
(210) between the ages of 18 and 40, who reported their location as the U.S. Gay and heterosexual
(211) people were represented in equal numbers. Their sexual orientation was established based on the
(212) gender of the partners that they were looking for (according to their profiles).

"Gay and heterosexual people were represented in equal numbers. "

Perhaps it is a flaw. Gay people are OVERrepresented in the sample.
Perhaps Gay people should be less than 10% in the sample.

If in real world heterosexual people are 90% of any REAL / REPRESENTATIVE sample of any real population, and 10% are only Gay and Bisexual, it will be easy to any algorithm to achieve 90% precision detecting heterosexual people!
It only needs to say all of them are heterosexual people and it will fail for a 10%,  i.e. 90% precision !


AGAIN the obsolete Big Five normative test.
http://onlinedatingsoundbarrier.blogspot.com.ar/2017/10/again-obsolete-big-five-normative-test.html

Finally the perfect dating algorithm? Of course NOT, Big Five test is OBSOLETE.
http://onlinedatingsoundbarrier.blogspot.com.ar/2017/02/finally-perfect-dating-algorithm-of.html