In a second step, they could answer an optional 30-item part (concerning past relationships and preferences for physical features)
The study design was a cross-sectional online survey implemented in the survey software Typeform v2 ( The study was online from . Subjects were told that the survey was about the qualities of their ideal partner(s). Participants younger than 18 were not able to participate in the survey. All participants completed a 14-item section focusing on demographic information and long-term preferences. In a third part, participants could answer questions about potential short-term partners, if they were willing to do so. Ten parallel language versions of the survey were developed: Chinese, Danish, English, French, German, Italian, Footnote 3 Japanese, Portuguese, Russian, and Spanish. Translators were native speakers of their respective languages who were contracted by the menstrual cycle tracking app Clue on a regular basis. A “four eyes” approach (one translator and one proofreader per language) was used. The survey was advertised via email campaigns to the respective user bases, messages within the Clue app, and social media channels.
Exclusion Variables
Exclusion criteria as outlined below were based on the following variables. Gender was measured with a categorical item “Do you identify as…” with response options (a) Woman, (b) Genderqueer/Nonbinary, (c) Man, (d) None of the above, (e) Prefer not to say, and (f) Other. Sexual orientation was measured with a categorical item “How would you describe your current sexual orientation?” with response options (a) Straight/Heterosexual, (b) Lesbian/Gay/Homosexual, (c) Bisexual/Pansexual, (d) Queer, (e) Asexual, (f) Prefer not to say, and (g) Other. Relationship status was based on the item “Select your relationships during the past 3 months” with response options (a) No romantic or sexual relationships during the past 3 months, (b) Short-term (casual) sexual relationship (e.g., hookups or one-night-stands), (c) New (less than 1 month old) romantic and/or sexual relationship, (d) Ongoing (longer than 1 month) uncommitted/nonexclusive romantic and/or sexual relationship, (e) Long-term committed/exclusive sexual relationship with one or more partners, and (f) Other.
