Measuring error and sampling variation in stereology: comparison of the efficiency of various methods for planar image analysis

Abstract

SUMMARY: An evaluation is made of the relative efficiency (precision of the final estimate per unit time of measurement on a given set of sections) of different methods for planar analysis aimed at estimating aggregate, overall stereological parameters (such as V v, S v). The methods tested are point‐counting with different densities of test points (4 ≤ P T ≤ 900 per picture), semiautomatic computer image analysis with MOP and automatic image analysis with Quantimet, for obtaining V v and S v estimates. One biological sample as well as three synthetic model structures with known coefficients of variation between sections are used. The standard error of an estimate is mainly determined by the coefficient of variation between sampling units (= sections in the present paper) so that measuring each sample unit with a very high precision is not necessary. Automatic image analysis and point‐counting with a 100‐point grid were the most efficient methods for reducing the relative standard errors of the V v and S v estimates to equivalent levels in the synthetic models. Using a 64‐point grid was as precise, and about 11 times faster than using a tracing device for obtaining the estimate of V v in the biological sample.