Sometimes, particularly when we are interested in the role of the number of observations n, we use the notation o for an estimator a It is then also appropriate to view On as a sequence of estimators o One for each value of n a The mean and variance of e are denoted Een and vare on respectively a We sometimes drop this subscript 0 when the context is clear◼ Sometimes, particularly when we are interested in the role of the number of observations 𝑛, we use the notation Θ෡𝑛 for an estimator. ◼ It is then also appropriate to view Θ෡𝑛 as a sequence of estimators. ❑ One for each value of 𝑛. ◼ The mean and variance of Θ ෡ 𝑛 are denoted 𝐸𝜃 Θ෡𝑛 and 𝑣𝑎𝑟𝜃 Θ෡𝑛 , respectively. ❑ We sometimes drop this subscript 𝜃 when the context is clear