A firm producing plate glass has developed a less-expensive tempering process to allow glass for fireplaces to rise to a higher temperature without breaking. To test it, five different plates of glass were drawn randomly from a production run, then cut in half, with one-half tempered by the new process, and the other half by the old. The two halves were then heated until they broke. The change in breaking strength was measured, new-old, for each pair. This is an example ofa matched pairs design.replication.a completely randomized design.