FAQ

Q: Recently, Affymetrix released a new set of Human Genome chips named U133 Set. How should I choose from the old set of Human Genome U95 Set or the new U133 Set?

A: Affymetrix uses different stretegies for probe selection in these two Human Genome Sets. Therefore, we recommend that users who are in the middle of projects with U95 finish out those projects with U95. Basically, if you need to perform direct comparisons between old images and new ones, you need to keep using U95.

If you have completed a project with U95 and going back to do similar studies but do not need to compare the data directly, then we recommend moving on to the U133 set, as it contains more information than U95 because of updates in the sequence database since the U95 release.

Please check the following resources for more information:

• Human Genome U133 Set (a general description of U133 Set)
• Human Genome U133 Set Technical Note (a detailed description of array design and probe selection of U133 Set and a comparison of sequence selection between U95 Set and U 133 Set)

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