The official scikit-learn certification, proctored by Probabl

The scikit-learn certification, Professional

The Professional Practitioner Certification targets working data scientists. Regularization, ensembles, feature engineering, nested cross-validation, and the judgement to pick a model and defend it to a stakeholder.

120 min proctored JupyterLite included Pass at 70%
Probabl
VERIFIED
02 / Professional SKL-P-2026
Certificate of Scikit-learn
professional practitioner
Level Mid-level data scientist
Credential type Verifiable credential
BY PROBABL
$349USD / exam fee
120 minexam length
30 + 1 labquestions
70%passing score
3 yearscredential validity
What we evaluate

Seven competencies of a working mid-level data scientist.

The Professional certification ensures certified professionals have both the conceptual understanding and practical skills of a mid-level data scientist.

01

Advanced ML Knowledge

Proficiency in a broad range of machine learning algorithms and the ability to select appropriate models for specific problems.

02

Programming Expertise

Strong coding skills in Python, with experience in optimizing code for performance and scalability.

03

Data Handling and Engineering

Ability to handle large datasets, including data extraction, transformation, and loading processes.

04

Feature Engineering

Experience in creating and selecting features to improve model performance.

05

Tuning and Optimization

Proficiency in hyperparameter tuning, model selection, and ensemble methods to improve model performance.

06

Critical Thinking

Approach complex problems systematically and evaluate multiple solutions, including diagnosing issues in a model pipeline.

07

Business Expertise

How ML projects align with business goals and how to translate technical results into actionable business insights.

Five topics. The shape of the Professional exam.

A step beyond Associate. Recognize when a model is regularized correctly, when a CV strategy leaks, and how to communicate that.

01

Machine Learning Concepts

The advanced mental model. Probabilistic outputs, regularization regimes, and what overfitting does to soft predictions.

  • Supervised and unsupervised, regression, classification, clustering, dimensional reduction
  • Model families: tree-based, linear, ensemble, neighbors
  • Regularization: L1, L2, Elasticnet
  • Hard and soft predictions, predict vs predict_proba
  • Overfitting and underfitting, impact on soft predictions
from sklearn.linear_model import LogisticRegression

clf = LogisticRegression(
  penalty="elasticnet",
  l1_ratio=0.5,
  solver="saga",
)
02

Model Building and Evaluation

Pick the baseline, regularize the noise, ensemble when warranted, and choose the metric that fits the problem.

  • Linear models as baselines
  • Handling correlation with regularization and feature selection
  • Bagging and boosting, the working ensemble methods
  • Choosing metrics for outliers and imbalanced settings
from sklearn.ensemble import HistGradientBoostingClassifier
from sklearn.metrics import average_precision_score

clf = HistGradientBoostingClassifier()
clf.fit(X_tr, y_tr)
ap = average_precision_score(
  y_te, clf.predict_proba(X_te)[:,1]
)
03

Interpretation and Communication

Read the plot, name the failure mode, explain it without using the word probability twice.

  • Visualizing results with intermediate matplotlib and seaborn techniques
  • Interpreting model outputs and performance metrics
  • Communicating results to non-technical stakeholders
from sklearn.metrics import PrecisionRecallDisplay

PrecisionRecallDisplay.from_estimator(
    clf, X_te, y_te,
).plot()
04

Data Preprocessing

Heatmaps, PCA, polynomial features, label propagation. The shaping work that makes a real-world dataset trainable.

  • Loading parquet datasets
  • Heatmaps and PCA for first look
  • Identifying strongly correlated features
  • Missing values in the target via label propagation
  • Feature engineering with PolynomialFeatures, SplineTransformer
  • Combining features with FeatureUnion
from sklearn.pipeline import FeatureUnion
from sklearn.preprocessing import (
  PolynomialFeatures, SplineTransformer,
)

union = FeatureUnion([
  ("poly", PolynomialFeatures(2)),
  ("spline", SplineTransformer()),
])
05

Model Selection and Validation

Group structure, non i.i.d. data, nested CV, stable hyperparameters across folds.

  • Cross-validation with group structure and non i.i.d. data
  • Hyperparameter tuning: GridSearchCV, RandomSearchCV
  • Stability of optimal hyperparameters via nested cross-validation
from sklearn.model_selection import (
  GridSearchCV, GroupKFold, cross_val_score,
)

inner = GridSearchCV(pipe, grid, cv=5)
outer = cross_val_score(
  inner, X, y, groups=g,
  cv=GroupKFold(5),
)
Certification ladder

Three levels. You are on the second.

Three certifications, each matching a level and a typical data scientist career path.

Associate Practitioner

Junior data scientist

Fundamental ML, preprocessing, evaluation

LEVEL 02 YOU ARE HERE

Professional

Mid-level

Regularization, ensembles, feature engineering, nested CV

Expert

Senior practitioner

Production ML, scaling, governance

Train where you will be tested

Get training with Skolar.

The Professional track on Skolar matches this exam: regularization, ensembles, feature unions, and nested validation, with notebooks and practice questions written by the scikit-learn team.

01 Completed
Associate Practitioner
8 lessons · ~24 h
02 2/10 complete
Professional
10 lessons · ~32 h
Continue ↗
03 Locked
Expert
12 lessons · ~40 h
The exam, in brief

Logistics, plain.

Everything you need to plan your sitting, in six lines.

Format Proctored online via Webassessor
Duration 120 minutes, 30 multi + 1 lab
Passing 70%, graded by topic area
Languages English, French coming Q4
Fee $349 USD, one retake included
Validity 3 years, renewable via Level 03
Frequently asked

Questions we get a lot.

Do I need the Associate before I sit Professional?
No. Associate is recommended as a stepping stone but not required. If you have a year or two of working data science with scikit-learn, you can sit Professional directly.
Is there a coding portion?
Yes. The Professional exam adds one hands-on lab on top of the multiple-choice questions. You will write and tune a small pipeline against a held-out dataset, in a sandboxed scikit-learn environment.
What if I do not pass?
One retake is included with your registration. After that, retakes are discounted. There is a 21-day cool-down between attempts so you can revisit weak topics on Skolar.
Is the credential verifiable?
Yes. Every passing candidate gets a credential ID and a public verification page on probabl.ai. Recruiters can confirm validity without contacting you.
Does it expire?
The Professional certification is valid for 3 years. Renew by passing the Level 03 (Expert) exam, or by re-taking Professional at a discount.
Ready when you are

Certify the work you already do, with scikit-learn.

120 minutes. $349 USD. Multiple-choice plus a hands-on lab, a credential issued by the maintainers themselves.