The variability of a press run as measured by Eastman Kodak Company\u27s Customized Color Analysis Target was studied and quantified in the areas of Pre-press requirements, Press Performance and Color Measurement. The test was conducted on a web offset newspaper press maintained to industry standards. The target was printed along with three halftones consisting of high-key, low-key and normal images. The halftone images were be used by the pressman to visually check and evaluate the press sheets during the run to maintain quality. A running color bar was also printed to provide densitometric readings. The test target was be evaluated using a computer controlled spectrophotometer and this information pertained to specific conditions of ink, paper, plates, U.C.R. , image type, etc.. The results are presented in the form of time series graphs which show the large degree of variability experienced by this press. The importance of selectivity in choosing a representative sample sheet is emphasized. The various events which can occur during a press run are documented by standard graphic arts variables measured by the test target. A comparison of initial prepress curves and suggested prepress curves is presented, and the effects of a second press run using the suggested prepress curves are predicted. The use of the quantity E as a quality criterion is explored. Lastly, methods for further study are suggested