Record chart performance is inherently relative, as they rank songs, albums and records in comparison to each other at the same time, as opposed to music recording sales certification methods, which are measured in absolute numbers. Comparing the chart positions of songs at different times thus does not provide an accurate comparison of a song's overall impact. The nature of most charts, particularly weekly charts, also favors songs that sell very well for a brief period; thus, a song that is only briefly popular may chart higher than a song that sells more copies in the long range, but more slowly. As a result, a band's biggest hit single may not be its best-selling single.