# Statistics and Data Analysis

Course
2022-2023

## Admission requirements

Familiarity with least-squares analysis (Praktische Sterrenkunde). Basic Python skills such as: making figures, working with functions, for-loops, and executing scripts (Programmeermethoden NA).

## Description

After you have conducted observations, and have finished reducing these into what we call a dataset, follows an important question: what can you learn from these data? Perhaps you have a certain hypothesis that needs to be tested. Or perhaps you have stumbled on a potential correlation between two observables of your sample. For each of these scenarios a set of tools is available to assess the relevance of your observations. In Statistics and Data Analysis you will get familiar with these assessment tools. By creating your own simulated datasets you will understand how and why these tools work, and also find out about their limitations. Finally, you will work with real astronomical datasets and apply what you have learned in practice.

## Course objectives

You will learn how to simulate data using a Monte Carlo approach, you will also test the boundaries of statistical methods, thus learning how to avoid common problems such as “overfitting” and the “look-elsewhere effect”.
After this course, you are able to:

• Simulate data using Monte Carlo methods.

• Apply two different statistical tests (Pearson’s r and Kendall’s tau) to measure the correlation strength between two variables.

• Apply two different statistical tests to examine the difference between two distributions (Kolmogorov-Smirnov and Anderson-Darling).

• Explain how these tests work and under which circumstances they can be applied.

• Explain the difference between a correlation and causal connection.

• Identify when the “look-elsewhere” effect is important in your data analysis.

• Quantify when you are “overfitting” the data.

• Ability to ask the right questions about your dataset.

• Visualizing key properties of a dataset in a clear figure.

• Structured thinking, including computational thinking and programming.

• Summarizing the properties of a dataset in a written report.

## Timetable

You will find the timetables for all courses and degree programmes of Leiden University in the tool MyTimetable (login). Any teaching activities that you have sucessfully registered for in MyStudyMap will automatically be displayed in MyTimeTable. Any timetables that you add manually, will be saved and automatically displayed the next time you sign in.

MyTimetable allows you to integrate your timetable with your calendar apps such as Outlook, Google Calendar, Apple Calendar and other calendar apps on your smartphone. Any timetable changes will be automatically synced with your calendar. If you wish, you can also receive an email notification of the change. You can turn notifications on in ‘Settings’ (after login).

For more information, watch the video or go the the 'help-page' in MyTimetable. Please note: Joint Degree students Leiden/Delft have to merge their two different

## Mode of instruction

• Lectures

• Exercise classes
All the exercise classes will involve writing and running scripts in Python. A laptop with a working Python environment is preferred for these classes.

## Assessment method

• Two homework sets (50%)

• Written report for final assessment (50%)

## Reading list

Background material will be made available during the course.

## Registration

From the academic year 2022-2023 on every student has to register for courses with the new enrollment tool MyStudyMap. There are two registration periods per year: registration for the fall semester opens in July and registration for the spring semester opens in December. Please see this page for more information.

Please note that it is compulsory to both preregister and confirm your participation for every exam and retake. Not being registered for a course means that you are not allowed to participate in the final exam of the course. Confirming your exam participation is possible until ten days before the exam.
Extensive FAQ's on MyStudymap can be found here.

## Contact

Lecturer: Dr. S. van Velzen
Assistants: Lotte Jansen, Puck Rooijakkers, Maan Kaan, Timo van Essen

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