Lomb and FT spectra are derived using algorithms,
and AR spectra are derived using an algorithm that is only slightly
slower for reasonable choices of model order. The essential
similarity of the Lomb, FT, and AR spectra given ideal inputs,
considered in light of their similar computational demands, suggests
that there may be little reason to choose one over any other.
When considering the less-than-ideal inputs endemic to HRV studies,
however, only the Lomb method produces robust PSD estimates in the
presence of noise and ectopy. The Lomb method avoids all of the
complications and pitfalls of resampling and replacement of outliers,
and introduces no drawbacks of its own; in consequence, it is the
method of choice for PSD estimation of heart rate.