An operational definition is a clear, concise, detailed definition of a measure. You need operational definitions when collecting all types of data. It is particularly important when a decision is being made about whether something is defective or not defective or whether a defect exists or not.
The varicella vaccine protects against chickenpox (varicella), a common and very contagious childhood viral illness. The varicella vaccine is given by injection when kids are between 12 and 15 months old. They receive a booster shot for further protection at 4 to 6 years of age. Kids who are older than 6 but younger than 13 who have not had chickenpox also may receive the vaccine, with the two doses given at least 3 months apart. Kids 13 years or older who have not had either chickenpox or the vaccine need two vaccine doses at least 1 month apart.
The measles-mumps-rubella-varicella (MMRV) vaccine is a four-in-one vaccine that protects against measles, mumps, rubella (German measles) and chickenpox. Two doses of the measles, mumps and rubella vaccine containing vaccine (as either MMR or MMRV) are required for children to attend school in Ontario.