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THE PRECISION OF UNBIASED ESTIMATES OF NUMERICAL DENSITY OF ENDOTHELIAL CELLS IN DONOR CORNEAS
Author(s) -
SPERLING STEFFEN,
GUNDERSEN HANS JØRGEN G.
Publication year - 1978
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.1978.tb06644.x
Subject(s) - variance components , accuracy and precision , statistics , sampling (signal processing) , variance (accounting) , mathematics , optics , physics , accounting , detector , business
The precision of estimates of central corneal endothelial density was studied in 16 human corneas stained by alizarine red and trypane blue. Estimates based on central counts and estimates based on peripheral counts were considered separately. The numerical density was estimated employing an unbiased sampling technique. From central counts estimates with an error of less than five per cent could be obtained. From peripheral counts a maximum precision of mean ± 12.2 per cent could be obtained. The theoretical maximum precision was calculated by application of a variance component model. The precision of estimates was calculated for 1, 2 and 4 test areas of different sizes. Economy of sampling was evaluated by comparison of the actual precision to the theoretical maximum precision of estimates.