A percentage says how one amount relates to another. Without the denominator, the reader may not know whether the figure describes all visitors, completed tasks, or a selected subset.
Write the group beside the percentage and check whether that group changed between comparisons. A rising share can happen while the underlying count falls if the total falls more. Counts and proportions answer related but different questions.
When comparing percentages, distinguish a change in percentage points from a relative percentage change. State the starting value and the method of comparison. A clear denominator gives a small number enough context to carry an accurate explanation.
A small working example.
Imagine two groups completing different numbers of attempts. A completion count alone cannot establish the same comparison as a rate with its total shown.
A note to keep beside it.
A column name can hide an assumption. Check units, missing values, and the counting rule before combining observations that only appear to be alike.
- Name the group behind the percentage.
- Compare counts as well as shares.
- Distinguish percentage points from relative change.
Follow a related question
Ask which situations the examples cover.
Examples shape the model’s taskDefine the start and end of the event.
Timing an ordinary eventKeep learning
Related background to continue exploring this subject.
NIST: statistical engineering NIST: the International System of Units
