Comparison of the relative signals between evenly- and randomly-distributed MM probes. The x-axis is the number of mismatches in the probes. The value in brackets is the percent identity of the 50 bp probe-target duplex. The y-axis is the average relative signal intensity of ten genes. Error bars indicate standard error of replicate arrays. Statistical tests were done between evenly and randomly distributed probes. An asterisk (*) indicates p-values ≤ 0.05, and double asterisks (**) indicate p-values ≤ 0.01 using a paired T-test.