Stigma constitutes a major barrier to HIV prevention, treatment and care. It may be due to the community where HIV-positive individuals live, to family members, to sexual partners or to health care providers. Potential study participants may be HIV-positive individuals, HIV-negative people, health care providers, etc. The way stigma is perceived or expressed may give rise to misleading answers due to social desirability bias. That is why the choice of the scale of measurement is so important.