If these results are good, jitter is usually low and may not require measurement. CD-R discs only imitate pits. Various dyes produce different simulation patterns. Experience shows that all parametric measurements and error rates may be satisfactory for a CD-R disc yet jitter may be unacceptable. Jitter therefore is an important test for CD-R discs.
Correlation can be difficult for many tests including jitter.
Three problems can result in poor correlation. First, differences in players and especially in the laser beam and optics can give different results. For example, results from a player having an ideal circular spot where the beam is focussed onto the track may not agree with a player where the spot is elliptical with the long axis in the direction of the track. An elliptical spot with the long axis perpendicular to the track can give results that differ from the previous two examples. Second, test electronics can affect test results.