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Data, Analytics and AI

Data analysis fundamentals

Before a query or a chart there is a question, and most weak analysis fails there rather than in the arithmetic. This page follows the analyst's workflow from framing a request to handing over a result somebody can act on, sets out the vocabulary that carries between every tool, and names the habit that separates a junior who reports numbers from one who knows what they are entitled to say.

Why this topic exists: Ask, prepare, process, analyse, share: the analyst's workflow as Google's programme and DP-900's core data concepts teach it, before any tool (SFIA Data analytics).

Data analysis is answering a specific question with records and stating how far the answer can be trusted. The glossary entry makes that second half its centre, and rightly, because a figure delivered without its limits will be quoted without them. Most of the craft is independent of software. SFIA describes the analytics skill as getting insight out of data, tidy or messy, and communicating it so that decisions follow. Microsoft's DP-900 opens its first skill area by asking candidates to tell structured, semi-structured and unstructured data apart, and transactional workloads from analytical ones. Those distinctions decide where data lives and how you may query it, long before anyone argues about tools.

Six steps, in the order they go wrong

  1. Ask. Turn a request into a question with a decision attached. How are sales doing has no answer; did the spring discount raise repeat orders among existing customers has one, and it tells you which data to fetch.
  2. Prepare. Find the sources, learn who produced them and for what purpose, and check that they cover the period and population the question needs.
  3. Process. Clean and reshape until the table can bear the question. This is data wrangling, and every decision taken during it belongs somewhere it can be run again.
  4. Analyse. Compare, aggregate, segment. Mostly this is SQL or a spreadsheet, and the discipline is to set each figure against a baseline instead of admiring it alone.
  5. Share. State the finding in one sentence, then show the chart that supports it, not the other way round.
  6. Act. Agree what the decision-maker will do with the result, and which result would have changed their mind. Without this step the analysis is merely a report.

Google's Data Analytics programme devotes one course to each of those steps, the wisest choice in its design: beginners who learn tools one at a time never see how a careless second step poisons the fifth. Every other framework on this site hides the same sequence under different names, from the modelling stages of machine learning to the preparation area of the Power BI exam.

Words that carry between tools

A handful of terms move an analyst between Excel, SQL, Python and any BI product. Granularity is what one row represents, whether a customer, an order or an order line, and most wrong totals come from joining two tables held at different grains. A dimension is something you group by, a measure something you add up. A metric is a measure with an agreed definition and an owner. A baseline is what you compare against, and a segment is a slice of the population chosen before you look at the results, never after. Learn these and the tools become interchangeable.

The beginner's mistake

Reporting a difference because it exists. Two numbers drawn from the same imperfect source will almost never match, and the real question is whether the gap exceeds the noise, the data errors and the seasonal wobble combined. Juniors present every movement; experienced analysts say which ones they would not act on. The natural next pages are SQL for analysis and statistics and experimentation, and IBM's free Data Fundamentals badge or Google's Data Analytics certificate test the ground covered here.

Next to this topic

Concepts to know

Glossary entries with the reason each one matters here.

Certifications that test it

Vendor exams and free certificates; facts, cost and the preparation path are on each page, and the certifications hub has them all.

Tools of the trade

Frequently asked

Do I need Excel before I learn SQL?
You need what a spreadsheet teaches: sorting, filtering, a pivot table and a feeling for when a total looks wrong. If work has already given you that, go straight to SQL. If not, a few weeks in a spreadsheet makes the ideas visible before you meet them as code.
What separates data analysis from business intelligence?
Analysis answers a question, often once. Business intelligence builds the models and reports that answer recurring questions for many people with no analyst in the loop. Analysts usually build the first version of a metric and BI makes it permanent; see data visualisation and BI.
How can I practise without a job in data?
Pick a public dataset about something you understand, write down the question and the decision it would inform before opening the file, and publish the whole chain: question, cleaning steps, result and what you would refuse to claim. One such write-up tells an employer more than a stack of completed tutorials.

Courses in the directory

1,806 courses are filed here; the top 6 by our ranking, details and the provider link on each course page.

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Last reviewed 26 September 2026 · Getting Digital