Contribution to Change Explained
Contribution to Change (CTC) allows you to measure the impact of each component on the change in overall performance. Currently, it is computed only for Spend, Revenue, Impression and Click metrics.
CTC allows you to identify the campaigns, keywords, or search terms which drove the most change in spend or revenue for the period in question, by sorting CTC by highest (if there's an overall increase), or lowest (if there's an overall decrease).
The formula for CTC is as followed:
Spend CTC = (Difference in Spend / Total Previous Spend) * 100
Revenue CTC = (Difference in Revenue / Total Previous Revenue) * 100
Jump to the below sections to learn more:
Getting Started with Contribution to Change
Contribution to Change is available for all consolidated dashboards: Campaigns, Keywords, and Search Terms.
You can find the data under when toggling Compare Mode in the top right Date Range.
How to Use Contribution to Change
The total CTC equals the Total Change %, i.e. how much the metric has changed period-to-period, and is the sum of all the individual components. Sorting CTC by descending order for a positive total CTC (and ascending order for a negative total CTC) helps you find the top contributor for the change in that period.