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Data Science


Admission requirements

No formal requirements.

The course builds on concepts from the bachelor courses Statistics (Ba2) and Data Mining (Ba3). Students are expected to program in Python.


Data Science places data mining, machine learning and statistics in context, both experimentally and socially. If you want to correctly deploy data mining techniques, you must be able to translate a (broadly formulated) question by a customer or a co-worker into an experimental set-up, to make the right choices for the methods you use, and to be able to process the data in the right form to apply those methods. After performing your experiments, you should not only be able to evaluate the results but also interpret and translate it back to the original question (e.g. by visualization). Socially, data science is of great importance because the media simplify many data-driven results and statistical research, often making mistakes. Thus, a lot of nonsense comes down on us and it is up to you, the data scientists of the future, to recognize, explain and correct that nonsense. This course is a combination of lectures and practical sessions, in which you take a hands-on approach to solving real-world data science problems.

Course objectives

A. Knowledge

  • You can explain the following machine learning concepts: supervised learning, unsupervised learning, classification, regression

  • You can list two advantages and two disadvantages of rule-based methods and of machine learning methods

  • You know and can explain the following experimental and statistical principles in your own words: bias, overfitting, cross validation, high-dimensional data, sparseness, dimensionality reduction, feature extraction, class imbalance.

  • You can describe typical use cases for Decision trees, kNN, SVM, Naïve Bayes and deep neural networks

  • You can explain the purpose and principles of feature extraction from semi-structured data, text data, image data and graph data.

  • You can explain the difference between engineered features and raw features, in content and in dimensionality

  • You know and can explain the use and importance of measuring the quality and reliability of human-labeled data.

  • You can give the definitions of the most important evaluation measures: Accuracy, Mean Squared Error, Precision, Recall, F1 and Mean Average Precision.

  • You know and can explain the benefits and challenges of big data.

  • You know and can explain the principles of responsible data science

B. Skills

  • You can recognize statistical nonsense in the media and erroneous visualizations, explain and correct it.

  • After completing the course, you can independently take the steps to set up and execute an experiment within data science, given a (broadly formulated) question:

  1. Task definition: You can create a clear definition of a task based on a general description of a task, consisting of (a) the research question, (b) whether the task is supervised or unsupervised, (c) whether it is a classification, regression or ranking task (or something else), (d) what the data are and (e) what the labels are;
  2. Data collection: If answering the question requests data is not given, then you can define what data you need and how to collect it. If you need explicit labels, you can set up a data annotation task for human raters;
  3. Data exploration: You can collect and visualize statistics about the data. You can calculate and interpret the inter-annotator agreement for annotated data.
  4. Pre-processing and feature extraction: You can write a Python script to read and process the data, extract features and store the feature vectors. You know how to engineer a low-dimensional feature set
  5. Model learning: You can apply unsupervised and supervised models to your data. You know how to make an informed decision on the type of classifier given the feature set. You can generate output for unseen data.
  6. Evaluation: You can correctly set up your model evaluation with a train / test split and cross validation if necessary. You can evaluate your output against human data. You know which evaluation measures you should use given the type of data and model. You can perform significance testing. You can do a sensible error analysis and feature analysis.


The most updated version of the timetables can be found on the students' website:

Mode of instruction

•• 14 lectures, 2x45 minutes

  • 1st 45 minutes: lecture

  • 2nd 45 minutes: practical session (working on data science problems in Python)
    This course is also followed by students from the course Data Science and Process Modelling from the I&E program (dr. Frank Takes).

Assessment method, including grading

The assessment of the course consists of a written exam (60% of course grade) and a practical part (40% of course grade). The practical part is subdivided in three assignments. The weights for the assignments are specified on the course website The grade for the written exam should be 5.5 or higher in order to complete the course. The weighted average grade for the practical assignments should be 5.5 or higher in order to complete the course. If one of the tasks is not submitted the grade for that task is 0.

The teacher will inform the students how the inspection of and follow-up discussion of the exams will take place.


You are expected to read 5 research papers during the course. The papers are announced during the lectures and will be published on Brightspace and the course website. The other materials are the course slides and the practical session instructions.

Signing up for classes and exams

You can enrol via uSis . More information about signing up for classes and exams can be found here .

There is limited space for students who are not enrolled in the BSc programme of Computer Science or the Minor Data Science. Please contact the study coordinator/study adviser.

Please also register for this course in Brightspace.


In MyTimetable kun je alle vak- en opleidingsroosters vinden, waarmee jij je persoonlijke rooster kunt samenstellen. Onderwijsactiviteiten waarvoor je in uSis staat ingeschreven, worden automatisch in je rooster getoond. Daarnaast kun je My Timetable gemakkelijk koppelen aan een agenda-app op je telefoon en worden roosterwijzigingen automatisch in je agenda doorgevoerd; bovendien ontvang je desgewenst per e-mail een notificatie van de wijziging.

Vragen? Bekijk de video-instructie, lees de instructie of neem contact op met de ISSC helpdesk.


Inschrijving voor vakken verloopt via uSis. Wanneer je je hier inschrijft voor een bepaald vak krijg je automatisch ook toegang tot de omgeving van dit vak via Brightspace.

Voor meer informatie over Brightspace kun je op deze link klikken om de handleidingen van de universiteit te bekijken. Bij overige vragen of problemen kan contact opgenomen worden met de helpdesk van de universiteit Leiden.



Suzan Verberne Riet Derogee, coordinator