Chapter 15.3, Problem 23E

A particular county employs three assessors who are responsible for determining the value of residential property in the county. To see whether these assessors differ systematically in their appraisals, 5 houses are selected, and each assessor is asked to determine the market value of each house. Explain why a randomized block experiment (with blocks corresponding to the 5 houses) was used rather than a completely randomized experiment involving a total of 15 houses with each assessor asked to appraise 5 different houses (a different group of 5 for each assessor).