What does Pairwise Deletion specifically involve?

Pairwise deletion is a method used in statistical analysis to handle missing data. It specifically involves using all available data for analysis by analyzing only the complete cases for each pair of variables being evaluated. Essentially, whenever a particular analysis (like a correlation coefficient) is performed, only the data available for those specific variables is considered. This means if a case has missing data for one variable but complete data for another, that specific pairwise comparison will still be conducted using the available data from those two variables.

The correct understanding is that pairwise deletion allows researchers to maximize data utilization by not discarding entire cases based solely on some missing values, thereby leveraging as much data as possible for the analysis of relationships between individual pairs of variables.