Figure 2

Spectral analysis of monthly HIV seropositive migrants entered Kuwait: 1997–2006: (a) Periodogram; it describes the amplitude and spacing of any sinusoidal patterns in the data. The value of the periodogram at a particular frequency (ω) is referred to as periodogram ordinate {I(ω)} as a function of ω; ω is measured as radians per month, which is convertible into portion of the cycle that is completed in one month). (b) Power spectrum; detects significant signals ( i.e . frequencies) buried in white-band noise.