Quality Measurements
ØArray
–Correlation between duplicate spot intensities
–Percentage of spots with negative signals
–Distribution of actual spot signal area vs. idealized
–Inter-array consistency
ØSpot
–Signal / Noise ratio
–Variation in pixel intensities within spots
Median signal intensity*
SNR
(signal-to-noise ratio) = ————————————
Median noise value
, where signal = foreground, noise = background
Sum of intensity value
* Mean
signal intensity = ——————————
Total number of pixels