Sound quality: This gives the quality of the recording of the most complete recording, as listed in the LiveNIRVANA Tour History. The rating is on the standard 10-point scale, with '10' being a perfect recording. This is the most objective rating of the five and is often the most important consideration for collectors.

Setlist: Concerts score highly here if they feature rare songs or only live perfomances of songs. Similarly, an unusual arrangement of a song, whether acoustic version of an electric song (or vice versa) or different song structure will be rated highly. Other postive factors include considerable variation from the usual setlist of the tour, and long concerts. The setlist is scored on a 10-point scale, with a long set featuring rare songs and one-offs scoring '10'. This is a reasonably objective rating.

Enthusiasm: Concerts score highly if the band appears to be enthusiastic and having fun. This can be difficult to judge, although a video recording can assist if one exists. Original or unusual stage costumes will augment the score here. Sloppy playing may be considered negative. The enthusiasm is scored on a 10-point scale, with an acrobatic, lively, happy band scoring '10'. This is more subjective than the above two ratings.

Banter: Concerts score highly if the band crack jokes or otherwise entertain the audience. Changing song lyrics for the audience's amusement is included in this category. We have also taken into consideration banter from anyone else on the stage introducing the band or making a guest appearance. The banter is scored on a 10-point scale, with a concert rich in anecdotes and wisecracks from all band members scoring '10'. This is also a fairly subjective rating.

History: This is a catch-all category which aims to cover everything missed in the above four categories. Some concerts may not have particularly unusual setlists or dynamic performances, but may be of interest for other reasons. For example, the first or last concert ever in a big city or country, first or last performance of a famous song, first or last concert of a big tour, first or last concert featuring a certain drummer, or any special guest appearances would be awarded a high score. The historical importance is scored on a 10-point scale, with '10' being awarded to a concert featuring high historical significance of some aspect of the performance. This is arguably fairly objective.

Overall: This is the simple mean of the above ratings, expressed as a percentage.

Note: Please do not attach too much importance to this figure: although we have endeavored to be as objective as possible, it is nevertheless a fairly arbitrary number. Some constituent ratings of the final score are manifestly unfair to short concerts (for example television appearances or support slots, which do not give much opportunity for banter or varied setlists). Sound quality is also harsh on concerts which have excellent sounding edits, but less good complete versions, for example Reading 1992.