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KajoData / Career & business

How to become a data analyst: learning, a project and your first applications

I explain how to connect tools through one project, document your skills and prepare to discuss the work of a data analyst.

Kajo RudzińskiPublished Updated 12 min read

A path connects islands with a table, archive, chart and project case before reaching a small lighthouse.

When someone asks me how to become a data analyst, I start with a task they want to be able to perform. A list containing Excel, SQL, Power BI and Python can indicate a direction, but it cannot tell you when learning becomes independent work. You need a situation where you take data, understand a question, check a calculation and explain the result to another person.

I suggest organising the plan around one manageable project. Each tool will help complete part of it, while the portfolio will show the outcome and the reasoning. I cannot promise an employment deadline. Starting points, available time and team requirements vary too much to compress the whole journey into a universal number of months. We can, however, define how to recognise progress.

The stages below connect learning to tasks and decisions you can revisit as your skills develop. Treat them as a sequence of demonstrable outcomes. Depending on your background and target role, you may move quickly through one stage and spend longer on another. The useful question is whether you can reproduce and explain its result without following every step of a tutorial.

First identify the work you want to do

An analyst may maintain recurring reports, explain a metric change, design a data model or support an operational team’s daily decisions. The scope depends on the organisation and role. Microsoft Learn describes both data preparation and stakeholder collaboration. I use that as an orientation point, then inspect the actual tasks an employer describes.

Collect several current vacancies suited to your location and working arrangements. Record responsibilities, tools, communication language and expected independence. Separate required skills from preferences. This sample does not describe the whole labour market, but it helps select a learning direction. You do not need to combine every requirement from every advertisement or pursue the most advanced-sounding title.

Also examine what you already know outside technology. Training coordination, logistics, sales or customer support can provide knowledge of the process behind the data. Describe a specific decision, information source and quality issue you can recognise. That knowledge does not replace SQL, but it helps you ask better questions and notice when a mathematically correct number has an incorrect interpretation.

Choose one project that connects the stages

Suppose you practise with synthetic class registrations. A coordinator wants to compare the use of available places with attendance among registered participants. These are different questions. The first uses available capacity as its denominator; the second uses active registrations. Before opening an application, decide how cancellations, cancelled sessions and incomplete attendance records should be handled.

For the initial exercise, assume two completed sessions, no cancelled sessions and complete attendance information. Active registrations already exclude cancelled bookings. Every number below is fictional. The table summarises sessions; an extension will use a separate session lookup and individual registration table so you can practise joining them.

Session Places Active registrations Attendances
A 10 8 6
B 20 10 5

There are thirty places, eighteen registrations and eleven attendances. Registrations fill 60% of capacity, while attendance among registered participants is approximately 61.1%. Attendances represent approximately 36.7% of all available places. Each number answers a different question. Keep this small example as a reference when moving the calculation into another tool and checking whether the output agrees.

Stage one: organise the data in a spreadsheet

A spreadsheet is convenient for inspecting a small table and checking results manually. I would begin with data types, filtering, sorting complete records, formula references and simple summaries, then add a PivotTable. The objective is to answer the coordinator’s question and identify which rows produced the result. Recreating a colourful report alone does not demonstrate that understanding.

Prepare a workbook with inputs, column definitions and a separate calculation area. Add another session and check that the summary includes it. Remove one attendance value and ensure that missing information does not automatically become zero. Change one thing at a time. This reveals which parts of the workbook are repeatable and which depend on manually extending formulas.

If similar exports arrive every month, explore Power Query for recording transformations. I would leave VBA until a real task requires workbook-specific automation. You do not need to master every Excel mechanism before progressing. You should be able to refresh your output, reconcile it with a sample and explain the conditions under which the process works.

Stage two: retrieve and combine data with SQL

SQL lets you describe the result you want from database tables. Begin with column selection, filters, grouping, ordering and an understanding of JOIN and NULL. Choose one available engine for practice and record which one you use. The PostgreSQL tutorial is an example of documentation covering relational foundations. Explore dialect differences through specific queries instead of starting with a ranking of engines.

In the class project, join registrations to the session lookup using an identifier. Verify that the lookup key is unique and that every registration finds its session. Compare record counts before and after the join. Only then count registrations and attendances. Two lookup rows for one identifier can multiply values without producing any syntax error.

I check readiness for the next stage by changing the question: show sessions without registrations, exclude cancelled bookings or identify unmatched records. You should be able to explain your choice of join. For initial analytical practice, I would concentrate on reading and checking data. Practise data modifications in your own environment, rather than trying a command against a company database merely because you have learnt its syntax.

Connect statistics to the question being asked

Initially, I want to understand proportions, means, medians, distributions and observation counts. In our example, attendance is 75% for A and 50% for B. Their simple mean is 62.5%, while overall attendance of eleven across eighteen registrations is approximately 61.1%. The aggregation method should reflect whether you mean the average session or all registrations combined.

Two sessions are insufficient to establish that a particular time of day or instructor caused lower attendance. That question requires additional data and a stronger comparison method. Learn to distinguish an observation from a causal explanation. A useful statement is: “This sample shows a difference, but I do not yet know what caused it.” Being precise about that boundary improves the analysis.

Stage three: build a report for a specific recipient

Choose Power BI or Tableau according to your target tasks and available environment. One is sufficient at the beginning. Learn model preparation, measure definitions, filter behaviour and clear presentation. Knowing the controls helps, but the recipient primarily needs an understandable answer. The dashboard guide explores those decisions in more detail.

The coordinator should see capacity, registrations and attendances alongside the corresponding rates. Show the reporting period and included session statuses. Test an empty filter and a single session. Open the report on a smaller screen, read its labels without adding your own commentary and ensure that colour is not the only way meaning is conveyed. Keep elements that support the agreed decision.

When following a dashboard tutorial, distinguish the method from its historical source and interface. A lesson using old mobility data may still demonstrate useful construction steps even if the original download or interface has changed. After reproducing a section, apply its operation to your own project. That tests whether you can use the idea with different data and a different analytical question.

Add Python when it solves a concrete problem

Python can help with repeatable file processing, exploring many variants and tasks requiring programming. I do not assume every first analytical role requires the same proficiency in it. Inspect your target vacancies. If understanding table joins remains the main difficulty, changing languages will not remove that gap. Establish dependable reasoning about the data first.

When you introduce Python, learn basic types, conditions, functions, files and error handling. Then use the pandas tutorials, which cover reading tables, selecting data and producing summaries. Recreating the spreadsheet result is a useful first check. Record environment versions and execution instructions so the answer does not depend on an accidental notebook-cell order.

Build a portfolio with evidence of your decisions

A project should show its question, data, transformations, checks, result and limitations. Put execution instructions somewhere immediately visible. A GitHub README provides a suitable introduction. Alongside the code, you can include a report screenshot and a short coordinator-facing note. The image alone will not let another person reproduce the calculation.

Identify your contribution: defining an active registration, checking missing attendance, validating the lookup or correcting a denominator. If the project began in a course, credit the source and describe your extension. Do not invent business impact that nobody measured. “Built a report with reconciliation checks and defined three metrics” is more defensible than attributing fictional revenue growth to a practice exercise.

A project case holds source cards, a visible processing mechanism and a result displayed as a simple chart.

Choose how to publish deliberately

Before public sharing, inspect the complete project, including source data and supporting files. Tableau Public makes published workbooks and data publicly accessible. Power BI Publish to web allows unauthenticated viewing and can expose model data beyond what the chart directly displays. This matters when selecting a portfolio destination.

For that purpose, I choose synthetic data or a source whose terms permit the intended use. A company report and its export require a separate decision about sharing. If the data cannot be published, provide an authorised process description or recreate the problem with fictional records. Real participant names are unnecessary for demonstrating SQL and an understanding of attendance definitions.

Test the link while signed out and read the project’s opening page. A visitor should know where to see the result and how to reproduce it. If an interactive report requires particular access, explain that and provide an authorised static preview. A working link and clear instructions belong to the demonstration of your skills; they deserve attention before the project is presented.

Describe experience through tasks and evidence in your CV

Instead of levels such as “Excel 80%”, explain what you can do. Mention preparing data, joining tables, defining measures and validating a result, then link to the project. Arrange the information for the target role. An operational-reporting position should see an example that allows that capability to be assessed, with your level of experience represented honestly.

Describe previous-industry experience concretely. Coordinating registrations may involve understanding cancellations and attendance lists; logistics work may involve recognising delivery exceptions. Separate actual past responsibilities from newly acquired technical skills. Do not rename an earlier position to imply a role you did not perform. A clear account of a real contribution is easier to defend than an impressive label.

Use your professional profile and contacts to support conversation

Explain which tasks you are seeking, what you can already demonstrate and where the project is available. Keep your profile consistent with the CV. You do not need to post daily or present yourself as an expert in every technology. A short explanation of a problem, a check and a finding can start a useful conversation with people working with similar data.

I would develop contacts through specific questions and substantive discussion. You could request feedback on a metric definition or project description. Respect the other person’s time by presenting a small, understandable part of the work. Do not assume a connection automatically produces a referral or job. Learning how target teams actually work is valuable in itself.

Organise learning around small outcomes

Reserve realistic time for three activities: understanding a concept, performing a task independently and checking the result. Adjust their proportions to your situation. The 80/20 idea can remind you to prioritise, but it cannot promise that a particular fraction of the material produces an identical result for everyone. If foundations take longer, the plan should accommodate that.

At the end of a session, record one outcome and the next problem. For example: “Joined registrations to sessions and reconciled the count; tomorrow I will test a session without registrations.” This makes returning after work or a break easier. If the plan repeatedly collapses, make the task smaller. One correctly checked operation provides more evidence of progress than hours of material watched without an independent attempt.

Select learning materials for the gap you need to close

Before starting a course, write down what you cannot yet perform independently. Inspect its syllabus, prerequisites and exercises. You need opportunities to practise and a way to evaluate the result. A certificate may document completion, but it does not replace a discussion of the project. After a section, check whether you can solve a similar task on different data.

Do not switch materials at the first difficult exercise, but do not spend months persisting with content at the wrong level either. Reduce the example, consult documentation and formulate a specific question. Return to a foundation if that is the gap. Add missing environment or dataset instructions if those are the obstacle. In either case, base the decision on the problem you identified.

Prepare to apply and discuss your work

You do not need to wait until you know every tool. Compare evidence of your skills with a particular vacancy and describe gaps honestly. Practise explaining the project’s objective, one difficult decision, the validation method and a limitation. Separately, practise solving a small task from a blank file rather than reproducing a memorised tutorial.

Ask about typical assignments, sources, review practices and support for learning the business. Record information from recruitment processes to improve subsequent applications. A single rejection does not explain the entire market or your capabilities. Look for concrete signals: an unclear project description, a missing skill or a mismatch between your expectations and the role’s scope.

Begin with one outcome: prepare the class data, calculate the three metrics and explain their differences. Then move part of the work into SQL, build a report and ask someone to reproduce the result. That sequence creates successive evidence of capability. If you get stuck, use the beginner-mistakes guide to select one thing to improve next.

Key takeaways

Which data analysis tool should I learn first?

Choose a tool suited to your first small task and target roles. A spreadsheet is convenient for inspecting and checking data, while SQL works with database tables. Learn through concrete results.

Must I learn Python before applying?

That depends on the role. Some positions place more weight on SQL, spreadsheets and reporting. Add Python when a target role requires it or it solves a specific project problem.

How long does becoming a data analyst take?

There is no dependable single timeline. Your starting point, practice time and target requirements all matter. Measure progress through independently completed tasks rather than weeks alone.

Kajo Rudziński

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