In R, a missing value is denoted by the symbol "NA". It represents a value that is not available or not applicable in a particular dataset or variable. Missing values can occur due to a variety of reasons, such as data entry errors, non-response in surveys, or data cleaning procedures.
In R, missing values are treated as a distinct data type and can be handled using functions such as
is.na() to identify missing values in a dataset,
na.rm argument to remove missing values from calculations, and
na.omit() to remove missing values from a dataset. It is important to handle missing values appropriately in data analysis to avoid biased or inaccurate results.