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Teacher since April 2026

Lin Zhao

Data cleaning, SQL, exploratory analysis and honest charts

9

tutors built

4.5Sample

average from 22 reviews

427Sample

lessons taught by their tutors

About Lin

I teach the part of data science that takes most of the time: getting data into a shape you can trust, querying it, exploring it and showing it honestly. I came to data from operations work, where reports drove real decisions and a wrong join could cost a week. I teach by handing you small, deliberately messy tables and asking what is wrong with them. I like checklists, plain SQL and simple charts, and I am suspicious of any analysis that skips looking at the raw rows. I enjoy helping spreadsheet users make the step into proper analysis.

Knows about

  • data cleaning
  • exploratory data analysis
  • SQL
  • window functions
  • visualisation
  • feature engineering
  • metric definitions
  • messy real world data
  • spreadsheets to analysis

Tutors by Lin

9 tutors

SQL for Analysis: First Queries

SQL for Analysis: First Queries

Write SQL that answers real questions, and check that the answer is rightBeginnerData science and statistics4.5(4)96 lessonsSampleLin ZhaoFreeFeature Engineering for Tabular Data

Feature Engineering for Tabular Data

Create features that help models learn, without leaking the answerIntermediateMachine learning4.3(3)72 lessonsSampleLin Zhao$7SQL Window Functions and Cohorts

SQL Window Functions and Cohorts

Rank, compare and track users over time with window functions and clean CTEsIntermediateData science and statistics4.7(3)61 lessonsSampleLin Zhao$6Metric Definitions That Hold Up

Metric Definitions That Hold Up

Define metrics precisely so every dashboard and team means the same thingAll levelsData science and statistics4.3(3)54 lessonsSampleLin Zhao$6From Spreadsheets to Data Analysis

From Spreadsheets to Data Analysis

Bring your spreadsheet skills into structured, repeatable data analysisBeginnerData science and statistics4.3(3)50 lessonsSampleLin Zhao$3Data Cleaning Fundamentals

Data Cleaning Fundamentals

Turn a messy table into data you can trust, with every change written downBeginnerData science and statistics4.7(3)49 lessonsSampleLin Zhao$4Charts That Tell the Truth

Charts That Tell the Truth

Choose, build and critique charts that show data honestly and clearlyBeginnerData science and statistics4.7(3)45 lessonsSampleLin Zhao$4Messy Real World Data

Messy Real World Data

Handle time zones, dirty join keys, shifting definitions and late data like a seasoned analystIntermediateData science and statisticsNewLin Zhao$7Exploratory Data Analysis Step by Step

Exploratory Data Analysis Step by Step

Explore a new dataset with a clear routine and turn what you notice into testable questionsBeginnerData science and statisticsNewLin Zhao$4

Recent reviews

What students said about Lin's tutors.

  • Rashid A.Sample

    Good beginner course. The row count checks saved me from sharing a wrong report.

    On SQL for Analysis: First Queries

  • Gustavo L.Sample

    We found four different definitions of active user across our dashboards. The specification template fixed months of arguments.

    On Metric Definitions That Hold Up

  • Annika S.Sample

    Great time window aggregates lesson. The cyclical encoding trick was simple and useful.

    On Feature Engineering for Tabular Data

  • Precious M.Sample

    I can now build retention tables without exporting to spreadsheets. Clear and precise.

    On SQL Window Functions and Cohorts

  • Valentina B.Sample

    I'm a marketer and can now pull my own campaign numbers. The fan out lesson explained a mistake I had made for months.

    On SQL for Analysis: First Queries

  • Karim J.Sample

    Out of fold target encoding explained clearly at last. My validation scores dropped a bit but now match production.

    On Feature Engineering for Tabular Data