Maximum Likelihood Estimation

Maximum Likelihood Estimation (MLE) is a method of estimating the parameters of a probability distribution by maximising a likelihood function, so that under the assumed statistical model the observed data is most probable

Specific methods are required to make inference under nonignorable nonresponse assumptions, that is when the value of the variable that is missing is related to some values which are not observed by the analyst (e.g. the missing values themselves)

When making inference with missing data, any statistical method must rely on either explicit or implicit assumptions about the mechanism which lead some of the values to be missing