Knowing how sure to be.
WHAT UNCERTAINTY MEANS
The finding could be wrong, and by how much.
WHAT AFFECTS IT
How many records How much variation How large the difference is Whether the data is representative
WHAT REPRESENTATIVE MEANS
The records reflect the whole, rather than a particular subset.
WHERE THAT FAILS
Analysing only customers who responded Analysing only one channel Analysing a period that was unusual
THOSE PRODUCE CONFIDENT WRONG ANSWERS
WHAT TO ASK
Who or what is missing from this data?
WHAT TO STATE WHEN REPORTING
How confident you are, and why.
WHAT LANGUAGE TO USE
"The data suggests" rather than "the data proves", where appropriate.
WHAT TO AVOID
Precision implying certainty Decimal places beyond what the data supports
THE DECIMAL POINT
Reporting a figure to two decimals from a hundred records implies accuracy that does not exist.
WHAT TO ROUND TO
What is meaningful.
