Clinical data munging involves manipulating raw clinical data to achieve an acceptable final form while respecting principles of clinical research ethics. It is an important process as analysts spend up to 85% of their time on data cleaning and preparation. The document outlines various phases in clinical data munging including screening for issues like missing or erroneous data, diagnosing the true nature of problems, and treating issues through actions like correcting, deleting, or leaving data unchanged. It also discusses specific challenges like dealing with missing values, extreme scores, erroneous dates and other errors, and recommends tools like Stata, R, and SAS that are well suited for clinical data munging.