An article These Chores Don’t Count? On Men’s Hidden “Second Shift” took a look at the sort of chores that are tracked in time use surveys. Here's what the author noted on how one source outlines it's definition of housework:
housework was defined as "core chores," or routine housework that people generally do not enjoy doing such as washing dishes, laundry, vacuuming floors and dusting. "Routine housework, like cooking dinner or making beds, was captured in diaries ... " says Stafford.
... Other activities such as home repairs, mowing the lawn, and shoveling snow were not in the study. "Items such as gardening are usually viewed as more enjoyable; the focus here is on core housework," says Stafford.
That's one way to ensure that your study reaches the "correct" conclusion.