TAILIEUCHUNG - Stereology for Statisticians

Before starting with the process of acquiring, correcting and measuring images, it seems important to spend a chapter addressing the important question of just what it is that can and should be measured, and what cannot or should not be. The temptation to just measure everything that software can report, and hope that a good statistics program can extract some meaningful parameters, is both naïve and dangerous. No statistics program can correct, for instance, for the unknown but potentially large bias that results from an inappropriate sampling procedure. Most of the problems with image measurement arise because of the nature. | 1 Stereology THE NEED FOR STEREOLOGY Before starting with the process of acquiring correcting and measuring images it seems important to spend a chapter addressing the important question of just what it is that can and should be measured and what cannot or should not be. The temptation to just measure everything that software can report and hope that a good statistics program can extract some meaningful parameters is both naive and dangerous. No statistics program can correct for instance for the unknown but potentially large bias that results from an inappropriate sampling procedure. Most of the problems with image measurement arise because of the nature of the sample even if the image itself captures the details present perfectly. Some aspects of sampling while vitally important will not be discussed here. The need to obtain a representative uniform randomized sample of the population of things to be measured should be obvious although it may be overlooked or a procedure used that does not guarantee an unbiased result. A procedure described below known as systematic random sampling is the most efficient way to accomplish this goal once all of the contributing factors in the measurement procedure have been identified. In some cases the images we acquire are of 3D objects such as a dispersion of starch granules or rice grains for size measurement. These pictures may be taken with a macro camera or an SEM depending on the magnification required and provided that some care is taken in dispersing the particles on a contrasting surface so that small particles do not hide behind large ones there should be no difficulty in interpreting the results. Bias in assessing size and shape can be introduced if the particles lie down on the surface due to gravity or electrostatic effects but often this is useful for example measuring the length of the rice grains . Much of the interest in food structure has to do with internal microstructure and that is typically revealed by a .

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• Stereology for Statisticians
• chemical analysis
• the overall chemical analysis
• chemical analysis of materials