Men who have sex with men with regard to trans women, people born either biologically male or with ambiguous genitalia who self-identify as female. Some sources consider trans women who have sex with men to be MSM, others consider women who are trans "alongside" MSM, and others are internally inconsistent (defining transgender women to be MSM in one place but referring to "MSM and transgender" in another). Determining the number of men who have ever had sex with another man is difficult. Worldwide, at least 3% of men, and perhaps as high as 16% of men, have had sex at least once with a man. These
Moving average "S" to "Y" as shown above, though other techniques exist, such as setting "S" to an average of the first 4 or 5 observations. The importance of the "S" initialisations effect on the resultant moving average depends on "α"; smaller "α" values make the choice of "S" relatively more important than larger "α" values, since a higher "α" discounts older observations faster. Whatever is done for "S" it assumes something about values prior to the available data and is necessarily in error. In view of this, the early results should be regarded as unreliable until the iterations have had time