Breakdown of Survey Sample by Period and Genre
Table B-1. Quotas by period and genre
Notes: The nominal quota of 100 recordings for each period is approximate because of the use of whole numbers for the component genre quotas. The 20 recordings from the National Recording Registry are to be divided among the genres as appropriate.
Notes on Quotas
Listings of early-1890s recordings are so rare in these discographies that virtually every listing encountered from that period was chosen. Most fall into the popular music category. The decade of the 1890s is one of the last frontiers of recorded-sound research, and it is only beginning to be seriously documented. Most researchers believe that because of the rarity of surviving recordings from this period, everything that still exists in playable form should be preserved.
For periods after 1895, we assigned quotas to each genre recorded during the period. In most cases, the quota for each genre was the same, although we made a few adjustments for genres that had very few listings and for those that reflected only part of a time block. Genre quotas were further broken down among the source discographies representing that genre and period on the basis of the estimated number of listings in each.
In some cases, the total for a time block exceeds the quota because of the addition of recordings from the National Recording Registry.
Table B-2. First-round sample by period and genre
Table B-3. Second-round sample by period and genre