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Region 4

Notes for region 4 accuracy assessment:

Sampling procedure followed general design. The geographic stratum was created using 30' x 30' grid cells. Primary sampling units (PSU) defined by non-overlapping, interior regions of aerial photographs acquired by the National Aerial Photograph Program (NAPP) were delineated within the stratum. A single PSU was selected from each grid cell, with all PSUs having an equal probability of being selected. The pixels selected within the first-stage PSUs were then stratified by mapped land-cover class, and a simple random sample of pixels was selected independently for each land-cover class. A total of 1,474 sample pixels were used for the accuracy assessment. Reference data collected from NAPP photos includes primary and alternate land-cover label where appropriate, land-cover heterogeneity in the vicinity of the sample unit, and a confidence rating of the photointerpreted land-cover label.