Heat map of scored semi-quantitative data for six qualitative variables from three independent observers.

<p>Observers evaluated Nissl-stained tissue sections (<i>n</i> = 204) from laboratory and field treatments using solutions containing 4% formaldehyde. Each column indicated with a small number (1, 2, or 3) represents an observer. Columns are grouped according to the qualitative variable being rated: presence of blood in tissue (A); evenness of stain (B); integrity of tissue at center of section (C); integrity of tissue at edges of section (D); clarity of lamination patterns (E); visibility of cell areas and nuclei (F). Tissue sections prepared under laboratory conditions are positioned on top (<i>n</i> = 166) and those prepared under field conditions on bottom (<i>n</i> = 38). The color code for the scored data is shown above the heat map. The black box outlines denoted with a ‘-‘ or a ‘+’ indicate selected regions of tissue ratings (negative or positive, respectively) that were largely uniform across observers.