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ML Academy

Introduced on day 6

Missingness mechanism

The process that decides which values are missing; MCAR, MAR and MNAR describe whether it depends on nothing, on observed data, or on the missing value itself.

In detail

The mechanism, not the missing share, decides what deletion and imputation do. Data can reject MCAR (missing rates differ across observed groups) but cannot prove MAR over MNAR; that distinction rests on knowledge of the process and on sensitivity analysis.