The following calculations are based on figures taken from the Office of National Statistics (ONS) 2021 census data on gender identity and Ministry of Justice (MoJ) statistics obtained by a FOI.
Transwomen
ONS data indicate that in England and Wales 47,572 people identified as transwomen.
MoJ statistics indicate the number of transwomen in prison for committing at least one sexual offence is 76.
This means the odds of a transwomen committing and being convicted of a sexual offence is:
76/47,496
This can also be written as 1 in 626 transwomen commit and are convicted of a sexual offence.
Men
ONS data indicate that in England and Wales there are 29,177,340 men.
MoJ statistics indicate the number of men in prison for committing at least one sexual offence is 13,234.
This means the odds of committing and being convicted of a sexual offence in the population of men is:
13,234/29,164,106
This can also be written as 1 in 2,205 men commit and are convicted of a sexual offence.
Comparing Transwomen to Men
We can compare the risk of being convicted of a sexual offence between transwomen and men by calculating the odds ratio (this is the odds of transwomen divided by the odds of men for committing and being convicted of a sexual offence).
The odds ratio is: 3.52 (95% CI: 2.81-4.42)
This can be interpreted as: compared to men, transwomen are 252% more likely to commit and be convicted of a sexual offence.
Women
ONS data indicates that in England and Wales there are 30,420,202 women.
MoJ statistics indicate the number of women in prison for committing at least one sexual offence is 125.
This means the odds of committing and being convicted of a sexual offence in the population of women is:
125/30,420,077
This can also be written as 1 in 243,362 women commit and are convicted of a sexual offence.
Comparing Transwomen to Women
We can compare the risk between transwomen and women of committing and being convicted of a sexual offence by calculating the odds ratio (this is the odds of transwomen divided by the odds of women committing and being convicted of a sexual offence).
The odds ratio is: 389.41 (95% CI:292.77;517.94)
This can be interpreted as compared to women transwomen are 38841% more likely to commit and be convicted of a sexual offence.
Comparing Men to Women
We can compare the risk between men and women of committing and being convicted of a sexual offence by calculating the odds ratio (this is the odds of men divided by the odds of women committing and being convicted of a sexual offence).
The odds ratio is: 110.43 (95%CI:92.59;131.70)
This can be interpreted as compared to women men are 10943% more likely to commit and be convicted of a sexual offence.
What do these statistics tell us?
These statistics indicate there is a large and statistically significant difference in the rates of convictions for transwomen versus men and transwomen versus women.
If transwomen are women then we would expect there to be no difference in the rate of sexual offending between the two groups. The fact that there is such a large statistical significant difference suggests that the two groups are distinct.
The fact that there is still a large statistically significant difference in the rates of offending between transwomen and men suggests that either transwomen do pose a greater risk of committing a sexual offence than men or that offenders identify as women once they have been convicted of a sexual offence.
What don't these statistics tell us?
These statistics do not tell us anything about individual transwoman. These statistics apply to populations and not individuals.
*The 95%CI = the 95% Confidence Interval (CI). The CI is a range of values around the statistic (in the case the Odds Ratio) that is believed to contain the true value of the statistic with a probability of 95%.
And for the CI calculation, which expected values were considered?
This math is completely wrong: 76/47596 is the probability that someone committed a sexual offense given that she is a trans woman.
odds =( 76/47596) / (1-(76/47596))
It would be helpful if the maths here was broken down for the non maths people. I have no idea what an odds ratio is. So have no idea of knowing if the maths is correct.
It would be more understandable to the public if there was an expression of 1 out of say 100 tran women is convicted vs 1 out of 1000 women or vs 1 out of 4000 men. Or whatever it works out as this is easier to see as a direct comparison.