Two-thirds of straight women and one-third of straight men are unwilling to date a bisexual person of the opposite sex, according to a YouGov poll published today, during Bisexuality Visibility Week. The poll illustrates how lingering stereotypes negatively affect people’s impressions of bisexual individuals.
The poll — which surveyed 5,983 Britons during late March, including 2,031 straight women and 1,517 straight men — found that 48% of all respondents had positive views of bisexual people and only 8% had negative views. The remaining percentage had neither a positive nor a negative view of bisexuals.
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When the survey asked straight women and men why they were unwilling to date a bisexual person of the opposite sex, most (16% and 19%, respectively) said they “just don’t” or claimed, “It’s just a preference.”
A nearly similar portion, 17% of straight women and 16% of straight men, said they felt like bi people are more inclined to cheat, or that they themselves would feel insecure that they’d be unable to provide a bi partner whatever they get from a same-sex partner.
Interestingly, 9% of straight women said they feel disgust or discomfort towards men with same-sex experiences, 8% worried about possible sexual health risks, and 10% of straight men said they considered bisexuality to be either religiously or morally “wrong.” Approximately 12-13% of all straight respondents said they just wanted their dating partner to be heterosexual.
If I ran you calculator correctly, I only need 25 bisexuals to answer for 72 million britons?
Without knowing the exact values you entered, I'm guessing that you calculated the number of samples needed to estimate proportion of bisexuals in the population +/- 5%. In other words, your survey with 25 random British individuals would net you an estimate of bisexual Britons in the range 0 to 6%.
In the context of this survey, you need a sample size of about 400 to get a 5% margin of error for the answers from the surveyed bisexual Britons, meaning that if 20% of those 400 British bisexuals answer "yes" to a survey questions, then the actual percentage (i.e. if you literally asked every British bisexual) is expected to be in the range 15% to 25%. YouGov has an article that it explains it better than I can: https://yougov.com/articles/2497-understanding-margin-error
I assume the calculator follows this math, you can check it if you want to understand better.