What Is Data Analysis
Understand what data analysis is, why it matters, and the workflow analysts follow from question to decision.
Learn to turn raw data into clear, reliable answers: from cleaning and spreadsheets to SQL, statistics, visualization and forecasting.
Understand what data analysis is, why it matters, and the workflow analysts follow from question to decision.
Tell apart categorical, numerical and ordinal data so you pick the right summary and chart for each.
Bring data into your analysis correctly from surveys, exports, APIs and files without losing or corrupting it on the way…
Find and fix duplicates, inconsistent entries and missing values before they quietly bias every result you compute.
Use formulas, references and sorting in a spreadsheet to explore data before reaching for heavier tools.
Summarize a column of numbers with the right measure of central tendency and know when each one misleads.
Go beyond the average with range, variance and standard deviation to describe how consistent or scattered data really is…
Design charts that show the truth quickly: the right encoding, honest axes and minimal clutter.
Match the chart to the question: comparison, trend, distribution, relationship or composition.
Summarize and reshape large tables into quick answers using rows, columns, values and filters.
Query a database directly with SELECT, WHERE, ORDER BY and GROUP BY to answer questions a spreadsheet cannot handle.
Combine data spread across multiple tables using INNER, LEFT and other join types.
Combine conditions precisely and order results so the rows that matter surface first.
Measure how strongly two variables move together, and understand why that alone never proves one causes the other.
Understand what a p-value actually means and how analysts decide whether a difference is real or just noise.
Draw a sample that actually represents the population you care about, and recognize the biases that quietly wreck it.
Read data ordered over time by separating trend, seasonality and noise.
Group users by shared traits or start date to see patterns a single overall average hides.
Store, parse and compare dates correctly, including time zones and calendar quirks that silently break analysis.
Clean, standardize and summarize text and category columns so they can be counted and compared reliably.
Find unusual values with simple rules like the IQR method and decide whether to keep, fix or remove them.
Rescale numeric columns to comparable ranges so no single unit dominates an analysis by accident.
Design a controlled experiment that isolates one change and tells you honestly whether it worked.
Fit a line through data to quantify how one variable predicts another, and read the result honestly.
Design a dashboard around a small set of well-defined KPIs that drive real decisions instead of vanity numbers.
Turn an analysis into a clear narrative with one message, the right evidence and a recommendation a reader can act on.
Handle personal data responsibly and recognize when an analysis, even an accurate one, can still cause harm.
Understand, at a conceptual level, how DataFrames, filtering and grouping work in pandas so code reads like your spreads…
Project a trend forward with simple, defensible methods and communicate the uncertainty honestly.
Plan and run a full analysis end to end, from a vague business question to a defensible, communicated answer.