Chapter 1 · Data Scientist

What a data scientist actually is

~7 min read

The phrase data scientist describes a family of related jobs, not a single one. Understanding the variants early helps you target your learning and, later, your job search. The clearest way to think about it is by what a person is accountable for.

Figure 2. Data scientist splits into three overlapping tracks, all built on a shared foundation.

1.1 The three tracks#

  1. Product and analytics data scientist. Uses SQL, metrics, experimentation, and product sense to drive decisions. At companies like Meta this role sits close to the product team. If you like framing questions and running experiments, this is your track.
  2. Machine learning and modeling data scientist. Builds models: feature engineering, training, evaluation, and often some deployment. If you like building systems that predict, this is your track.
  3. Applied or research scientist. Invents or adapts methods, usually with an advanced degree, at research-heavy organizations. If you like novel problems and publishing, this is your track.

1.2 Data scientist versus neighboring roles#

RoleAccountable forKey difference
Data analystInsight and reportingBusiness-facing; lighter statistics and modeling
Data scientistDecisions and modelsStatistics, experimentation, and ML depth
ML engineerProduction systemsSoftware engineering; deploys models at scale
Analytics engineerTrusted data modelsBuilds the tables analysts and DS consume (dbt)
Research scientistNew methodsAdvanced degree; invents techniques

1.3 The modern data science workflow#

Whatever the track, the work follows a recognizable loop. Most beginners imagine data science is mostly modeling. In reality, framing the problem and preparing the data take the majority of the time, and communicating the result is what makes the work matter.

Figure 3. The data science workflow. Framing and data preparation dominate the real timeline, not modeling.

1.4 The skills this guide builds#

Skill areaWhat you will learn hereChapter
Python for datapandas, NumPy, the analysis workflow2
Statistics & probabilityDistributions, inference, Bayes3
EDA & cleaningExploring and preparing real data4
SQLQuerying data for analysis5
Machine learningCore concepts and five algorithms6 and 7

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