I was reading the user's guide of SPSS on missing value analysis and I found the terms monotonic and non-monotonic pattern of missing values. The terms are not quite clear to me. They used
telco_missing.sav data file to show a graph from which they comment:
If the data are monotone, then all missing cells and nonmissing cells in the chart will be contiguous; that is, there will be no “islands” of nonmissing cells in the lower right portion of the chart and no “islands” of missing cells in the upper left portion of the chart.
I didn't either understand that. I hope someone will be kind enough to show me how a monotone and non-monotone patterns does look like and tell me how do I understand it a little more clearly.