Nested and Grouped tables look very similar. Both have subcolumns and no X column. But they are used in very different ways.
The key point is the arrangement of replicates:
•In a Grouped table, replicates are placed in side by side subcolumns.
•In a Nested table, replicates are stacked into subcolumns.
We suggest you use the tutorial data sets and pay attention to how the data arrangement matches the experimental design.