Web Analytics with Google Analytics 4Reports and explorations · Lesson 15 of 20

From data to insight: an analysis workflow

Article · 10 min · 8 min lecture

Video lecture

From data to insight: an analysis workflow

14 chapters · about 8 min · full transcript

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Chapter 1 of 14

From data to insight

  • Observation versus insight
  • Question-first workflow
  • Decomposition
  • Signal versus noise
  • AI for hypotheses, safely
  • Presenting

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Chapters

Reports are not insights

"Sessions rose 12%" is an observation. "Sessions rose 12% because a creator's video drove new mobile users, but they converted at half the site average because the landing page is slow on mobile — fixing speed could unlock significant revenue" is an insight: it explains, quantifies and points to action.

The question-first workflow

1. QUESTION   What decision will this analysis inform? Who makes it, by when?
2. CONTEXT    What changed? Campaigns, releases, seasonality, tracking changes.
3. HYPOTHESES List 2-4 plausible explanations BEFORE opening GA4.
4. EVIDENCE   For each hypothesis, which report/exploration/segment would confirm or refute it?
5. ANALYSIS   Run the checks; note data-quality caveats.
6. SO WHAT    Quantify impact (illustratively if estimates) and recommend an action.
7. FOLLOW-UP  How will we know if the action worked?

Writing hypotheses first protects you from confirmation bias — hunting through reports until something supports what you already believed.

Diagnosing a change: the decomposition method

When a KPI moves, decompose it:

Revenue = Sessions x Conversion rate x Average order value
Leads   = Sessions x Lead rate

Then ask which factor moved, and within that factor, which segment (channel, device, country, landing page, new vs returning) explains most of the change. A 15% revenue drop might be entirely one channel's sessions, or entirely a mobile conversion-rate drop — very different fixes.

Worked example: the revenue dip

Illustrative numbers for an online homeware store, comparing two equivalent weeks:

FactorWeek AWeek BChange
Sessions50,00049,000-2%
Conversion rate2.0%1.6%-20%
AOV6061+2%
Revenue60,00047,824-20%

Traffic and order value are stable; conversion rate explains the drop. Segmenting conversion rate by device shows desktop unchanged but mobile down sharply, starting on the day of a site release. Checking the release notes reveals a new address-lookup component. Path and funnel explorations confirm drop-off at add_shipping_info on mobile. Recommendation: roll back or fix the component; estimated weekly revenue at risk is the gap between the two weeks.

Separating signal from noise

Small numbers swing randomly. Before reacting:

  • Compare against a longer baseline (for example the same weekday average over several weeks).
  • Check volume: a conversion rate based on 30 sessions is unreliable.
  • Check tracking changes and annotations — did measurement change rather than behavior?
  • Consider seasonality and events (paydays, public holidays, school terms, religious festivals, sales events).

Presenting insights

Use the "what, so what, now what" structure:

WHAT:     Mobile conversion rate fell from 2.1% to 1.3% since the 14th.
SO WHAT:  Illustratively ~ one-fifth of weekly revenue at risk; desktop unaffected.
NOW WHAT: Roll back address lookup (dev, today); re-test funnel (analytics, tomorrow).

Lead with the conclusion. Put charts after the story, and show only charts that support it.

Beyond GA4

Some questions cannot be answered in GA4 alone: profit (needs cost of goods), customer lifetime value across offline channels, or lead quality (needs CRM). Good analysts know when to pull in other sources — CRM exports, ad platform cost data, BigQuery joins — and state clearly which numbers came from where.

Hands-on: decomposition in a few lines of pandas

Export two comparable weeks (from the Data API, BigQuery or a report download) with sessions, orders and revenue by segment, then let the code show which factor moved:

import pandas as pd

df = pd.read_csv("weeks.csv")      # columns: week, device, sessions, orders, revenue
agg = df.groupby("week")[["sessions", "orders", "revenue"]].sum()
agg["cr"] = agg["orders"] / agg["sessions"]
agg["aov"] = agg["revenue"] / agg["orders"]
print(agg.round(4))

by_dev = df.pivot_table(index="device", columns="week", values=["sessions", "orders"], aggfunc="sum")
cr = by_dev["orders"] / by_dev["sessions"]
print((cr["B"] - cr["A"]).sort_values())   # which device's conversion rate moved most

Hands-on: using Ask Advisor or a general AI assistant safely

AI can speed up the "hypotheses" and "so what" steps. Use a prompt that keeps it honest:

Context: GA4 property for a UK homeware store. Weekly revenue fell ~20% (week B vs week A).
Data (aggregated, no personal data): [paste the decomposition table and device split]
Known events: site release on the 14th (new address lookup), no campaign changes.
Task: 1) list 3-4 hypotheses ranked by fit with the data, 2) for each, the GA4 report or
exploration that would confirm or refute it, 3) draft a what/so what/now what summary using
ONLY the numbers provided. Mark any estimate as illustrative. Do not invent data.

Inside GA4, Ask Advisor (beta) can answer "why did revenue drop last week?" directly from your property. Treat its answer as a hypothesis generator: open the report it cites, confirm the numbers, and check the release log and change log yourself before presenting.

Second worked example: a Riyadh travel agency's lead drop

Leads fall 30% (illustrative) in a week. The decomposition shows sessions stable and lead rate down only on Arabic-language pages. A path exploration shows Arabic users reaching the form and leaving. The form's Arabic validation message had broken after a translation update, blocking submission. Fixing it restored the lead rate. The written insight took five lines, and the recommendation had an owner and a deadline.

Common mistakes

  • Opening GA4 without a question and "looking for insights".
  • Reporting every metric that changed instead of the ones that matter.
  • Explaining random noise as meaningful trends.
  • Recommendations without owners or deadlines.
  • Forgetting to check whether tracking changed.
  • Mixing up correlation and causation: two metrics moving together does not prove one caused the other. Where the decision is significant, propose an experiment to confirm.
  • Presenting false precision, such as revenue impact to the last unit, when the inputs are estimates. Round sensibly and label estimates as illustrative.

Timeboxing analysis

Analysis expands to fill the time available. Agree a timebox with the decision-maker up front — for example, two hours for a weekly anomaly, two days for a quarterly channel review. If the timebox runs out, report what you know, the confidence level, and what extra evidence would change the recommendation. A good-enough answer delivered before the decision beats a perfect one delivered after it.

Analysis quality checklist

Key takeaways

  • An insight explains, quantifies and points to an action.
  • Write hypotheses before opening reports to avoid confirmation bias.
  • Decompose KPIs (sessions × conversion rate × AOV) to find what really moved.
  • Present as what, so what, now what — conclusion first.

Check your understanding

Quick questions to lock in the lesson. They don’t count towards your certificate.

  1. Revenue fell 20% while sessions and AOV were flat. Where should you look next?
  2. Why write hypotheses before opening GA4?
  3. Which statement is an insight rather than an observation?

Put it into practice

Take a real KPI change from a site you know, decompose it, write three hypotheses and a what / so what / now what summary.

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