The invention comprises a method and apparatus for selecting optical pathways sampling a common tissue layer, such as the dermis, of a person for analysis in a noninvasive analyte property determination systemy, comprising the steps of: probing skin with a range of illumination zone-to-detection zone distances with at least two wavelength ranges, which optionally overlap, and selecting, using a metric, illumination zone-to-detection zone distances having mean optical pathways probing the common tissue layer, such as without the mean optical pathways entering the subcutaneous fat layer of the person. Optionally, the skin tissue layers are modulated and/or treated via tissue displacement before and/or during data collection.