How Frequently Does Transsexualism Occur?

by Lynn Conway

Copyright @ 2001-2012, Lynn Conway. All Rights Reserved.

Original article posted on January 30, 2001.

Updated version posted on December 17, 2002.

Ongoing reactions/commentary updated through 4-02-12.

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This page contains a 2001 investigative report (see below), in which Lynn Conway raised a widespread alert about gross underestimations of the prevalence of transsexualism by the psychiatric community. Lynn also posted her main findings in a summary page, to enable quick access to the key ideas.

As a follow-on to that work, Prof. Femke Olyslager of Ghent University (Belgium) and Lynn Conway did a systematic analysis of all the early studies on trans prevalence. They discovered and exposed major errors in most of those studies, presenting their findings at the 2007 WPATH symposium and submitting that paper for publication in IJT.

A condensed version of their results, focusing on the prevalence of transsexualsim in the Netherlands and Belgium, was published in 2008 in a peer reviewed paper in Tijdschrift voor Genderstudies: Olyslager, F. and L. Conway, "Transseksualiteit komt vaker voor dan u denkt. Een nieuwe kijk op de prevalentie van transseksualiteit in Nederland en België," (Transsexualism is more common than you think. A new look at the prevalence of transsexualism in the Netherlands and Belgium), Tijdschrift voor Genderstudies, Vol. 11, no. 2, pp. 39-51, 2008.

In 2011, Prof. Sam Winter of Hong Kong University and Lynn Conway analyzed further emerging trans-prevalence data from around the world, documenting their findings in Prof. Winters' TG-Asia website:

Numbers count, even if psychiatrists can't! - Lynn Conway

Timeline: The following timeline tracks the sequence of events as these studies unfolded and were reacted to by the psychiatric/psychological community.

01-30-01: Lynn's original investigative report was completed and posted on January 30, 2001. 12-17-02: An updated, more tutorial version was posted on December 17, 2002.

09-06-07: In early 2007, Lynn Conway and Femke Olyslager analyzed all early research reports on the prevalence of transsexualism. They found that systematic errors in all those reports had led to widespread reporting of unreasonably-low prevalence numbers, and to a group-think view amongst psychologists that transsexualism is "extremely rare". Upon applying correct calculations to the data in the old reports, Olyslager and Conway discovered that data confirmed Conway's hypothesis (in 2001) that transsexualism is far more common than previously suspected - reporting their results in the following paper:

Olyslager, F. and Conway, L., “On the Calculation of the Prevalence of Transsexualism”,

presented at the WPATH 20th International Symposium, Chicago, Illinois, September 6, 2007

[Submitted for publication in the International Journal of Transgenderism].

See also Reviewers' Notes and Powerpoint Slides ( NL ) for that paper.

07-03-08: A condensed version of the Olyslager and Conway 2007 paper, focusing on the prevalence of transsexualism in the Netherlands and Belgium, was then published in the peer reviewed Dutch Journal for Gender Studies on July 3, 2008 (cover-contents, summaries in English, link to paper, authors):

Olyslager, F. and L. Conway, "Transseksualiteit komt vaker voor dan u denkt. Een nieuwe kijk op de prevalentie van transseksualiteit in Nederland en België," (Transsexualism is more common than you think. A new look at the prevalence of transsexualism in the Netherlands and Belgium), Tijdschrift voor Genderstudies, Vol. 11, no. 2, pp. 39-51, 2008.

08-17-08: On August 17, 2008 the American Psychological Association published the Report of the Task Force on Gender Identity and Gender Variance, posting it on the internet as a PDF file with considerable fanfare in the press.

Upon reading the APA report, we found that it grossly underreported the prevalence of “gender identity disorder” by a factor on the order of 10 to 20. The underreporting resulted from deliberate misuse of clinical definitions and failure to mention known calculation errors in cited sources. The unreasonably low values were stated to three significant figures, as if those values were precisely accurate – while well-known sources of estimation error went unmentioned. The Task Force openly dismissed the work by Olyslager and Conway that had exposed large errors in earlier studies, calling it a “minority position” - further insinuating that citations by "transgender activists" reduced its validity. The Task Force also failed to mention recent scientific studies reporting far higher-levels of GID prevalence, including the peer reviewed Olyslager and Conway paper of 7-03-08.

08-27-08: In reponse to the APA Report, Lynn posted the following investigative report, exposing the falsification of results by the APA Task Force:

"Falsification of GID prevalence results by the APA Task Force on Gender Identity and Gender Variance", An Investigative Report by Lynn Conway, LynnConway.com, August 27, 2008

How Frequently Does Transsexualism Occur? by Lynn Conway http://www.lynnconway.com/ Copyright @ 2001-2002, Lynn Conway. All Rights Reserved. Original article posted on January 30, 2001. Updated version posted on December 17, 2002. Abstract