Histrograms for the number of probes per probe set. Both plots are histogram, the values on the y axis are relative frequencies. (top) Histogram of the number of probes on the U133A chip matching a particular RefSeq transcript. A clear peak can be seen for 11 probes, which corresponds to the number of probes in a probe set most commonly found in the original mapping. This set is called Alt1 in the last part of the section Results. (bottom) Histogram of number of RefSeq transcripts matching a single probe (log scale). Most of the probes can be seen matching only one RefSeq. In both plots, the probes associated to human 'ALU' repeats were filtered out.
Gautier et al. BMC Bioinformatics 2004 5:111 doi:10.1186/1471-2105-5-111