BACKGROUND FLOURESCENCE IN CDNA MICROARRAY EXPERIMENTS

Typical cDNA microarray experiments are affected by several sources of noise. Background fluorescence is measured to estimate the amount of fluorescence due to coating molecules and, eventually, to dying molecules leaked from spots. In this contribution, statistical models are used to smooth raw background values in order to improve the normalization of raw data and to test for the presence of a trend surface induced by sources of bias like the confocal microscope. Let DCR2 be the two-dimensional array area in which n background values Z(xi),i=1,...,n are observed from the process Z(x),x ED. By assuming the presence of a trend surface, we have Z(x)=h(x)+e(x), where h(x)=constant if the trend is absent, and where e(x) is a zero mean spatial stochastic process with pre-assigned covariance.