From same Gender disparities paper
In July 2016, the BJS began identifying transgender people among NCVS respondents aged 16 years or older.3 Gender identity was measured with 2 questions: sex assigned at birth (male, female, and don’t know) and current gender identity (male, female, transgender, or none of these). Respondents are categorized as transgender if they identified as transgender or their current gender identity was male or female and was different from their assigned sex at birth. Respondents are categorized as cisgender if their current gender identity matched their assigned sex at birth. In the 2017–2018 NCVS, about 0.10% (n = 420) people were thus classified as transgender and 99.9% (n = 435 061) were cisgender.
The approach used to separate out the transgender cohort seems sensible
The numbers of members of each cohort
not transgender - 435,061
transgender man (TIF) - 181
transgender woman (TIM) - 188
prefer not to say - 51
This is odd because an estimated 1% of people aged 13 and over in USA are trans. This would suggest that far fewer than expected people from the trans community are suffering victimization - if the spread of victimization was even between populations then you would expect a 1% reported figure.
The small number of people in the transgender cohort leads to the wide 95% confidence bands in this graph (below)
So whilst the general population data is reasonably accurate, the same can't be said of the transgender statistics. It would have been useful if this were pointed out in the Williams Institute article (and others)