Collecting and understanding the metrics that matter
Collecting and understanding the metrics that matter
This domain tests your ability to read Google Ads and GA4 metrics correctly, connect them to business outcomes, and avoid false comparisons. Questions often hinge on definitions, attribution windows, and which metric actually answers a diagnostic question.
Core rules
- In Google Ads, match the metric to the question. CTR = clicks ÷ impressions; average CPC = cost ÷ clicks; conversion rate = conversions ÷ clicks; CPA = cost ÷ conversions; ROAS = conversion value ÷ cost. Impressions, impression share, top-of-page rate, and absolute top rate diagnose visibility; lost IS (budget) and lost IS (rank) separate money from competitiveness.
- Distinguish Conversions from All conversions. The Conversions column counts actions you have marked primary and included in bidding; All conversions can include secondary actions and other sources. View-through conversions and cross-device conversions are modeled or matched and should not be added naively to click conversions.
- GA4 metrics are session- and event-based. Sessions count visits; engaged sessions last over 10 seconds, include a conversion event, or include two or more page views. Engagement rate = engaged sessions ÷ sessions. Key events count marked events; key event rate = key events ÷ sessions. Revenue metrics include total revenue, purchase revenue, and ad revenue.
- Attribution changes the number. Google Ads conversion reporting uses the conversion action’s attribution model and lookback windows; GA4 reports use reporting attribution settings that can differ. Data-driven, last-click, and first-click will not agree, and neither will a 30-day click window and a 7-day window.
- Check data quality before acting: consent mode and modeled conversions, GA4 thresholding, internal traffic filters, currency and time zone, and conversion lag. A metric that is still filling in is not a trend.
Worked example
A search campaign has 100,000 impressions, 2,000 clicks, cost of $4,000, 80 conversions, and $16,000 conversion value. CTR is 2%, average CPC is $2, conversion rate is 4%, CPA is $50, and ROAS is 4.0. GA4 shows 95 purchase key events for the same period. Reasoning: the gap is plausible because Ads uses the conversion action’s data-driven model and 30-day click window, while GA4 reporting may use a different attribution setting and include or exclude modeled data. Before cutting budget, compare like-for-like windows and check whether the Ads action is primary.
Traps
- Comparing CTR or CPA across Search, Display, and Video as if benchmarks were interchangeable.
- Treating All conversions as incremental, when secondary actions may inflate the total.
- Using last-click GA4 revenue to judge a data-driven Ads campaign without reconciling the settings.
- Reading a 7-day report during a 30-day conversion window and calling the campaign a failure.