unbiased estimation

• How to Find an Unbiased Estimator
  An estimator is unbiased when its expected value equals the target for every parameter value; identify the model, compute its expectation, and verify it.
• How to Find the UMVUE of an Exponential Parameter
  For an i.i.d. exponential sample, the UMVUE depends on whether theta is the scale or rate: use the sample mean for scale and (n−1)/sum Xi for rate.