A Guide to Collecting, Processing and Analyzing Online Job Ad Data

Logos of Bertelsmann Stiftung and Bundesinstitut für Berufsbildung
Online job ads (OJA) can provide detailed labor market insights relevant to the public, private, and civil society sectors. This project highlights which challenges arise in analyzing OJAs, which methods allow for a meaningful interpretation, and which quality criteria to report for transparency purposes. Furthermore, we want to highlight experts in this field and good practices. The content is geared towards the German context, but most of the insights should be transferable to other countries.

About This Project

The project was initiated by Bertelsmann Stiftung and the Federal Institute for Vocational Education and Training. The project manager and main author is Johannes Müller (&effect data solutions) who has extensive experience in working with online job ad data.
The project results are published via printable and interactive reports under an open-source license. The interactive website allows the content to develop further over time and remains open for feedback and suggestions.
Thank you very much to everyone who has already contributed or provided feedback to the project. This includes among others the Federal Institute for Vocational Education and Training (BIBB), the Institute for Employment Research (IAB), the HRM & Employment Relations team at the University of Innsbruck, the Stellenmarktmonitor team at the University of Zurich, and the IW Cologne.


The guide is designed for quick navigation between the sections. There are different ways to read the guide: The recommended way is to follow the path of one online job posting through the whole process until it is included in the analysis: In this project, we call it the OJA Lifecycle.
Alternatively, if you have a direct question or challenge, you can navigate to the related section at Overview - Challenges. To get an overview of all methods discussed, start with the Overview - Methods.
A quick overview over the project and the reasoning behind the design decisions by the author Johannes Müller

What Can We Learn from Online Job Ads?

Online job ad (OJA) analysis is the process of analyzing job advertisements posted online. The goal is to understand the skills, qualifications, and requirements that employers most demand. This can be done using automated tools that can analyze large volumes of job ads and identify trends and patterns.
Some of the many reasons why one might want to analyze OJAs include:
  • Identifying the most in-demand skills and qualifications: By analyzing job ads, it is possible to identify the skills and qualifications that employers most often mention. This can help job seekers understand what they need to focus on to be competitive in the job market. Furthermore, it can help education providers develop evidence-based programs.
  • Understanding the types of positions that are available: By analyzing the job titles and descriptions in job ads, it is possible to get a sense of the kinds of positions that are available and the industries in which they are located.
  • Identifying any trends or changes in the job market: By analyzing job ads over time, it is possible to identify any changes or trends in the job market. For example, suppose the number of job ads for a particular skill or qualification increases or decreases significantly. In that case, this may indicate a change in the demand for that skill or qualification.
  • Comparing job ads across different locations or industries: By comparing job ads from different areas or industries, it is possible to get a sense of the differences in the types of positions and qualifications sought in other parts of the country.
  • Understanding discriminatory language in job ads: Identifying language-based barriers to the attraction of job seekers generally and of particular groups (e.g., women, older workers, people with migration backgrounds). Terminology of (online) job ads is shaped by bias, excluding qualified job seekers from applications and leading to the perpetuation of inequalities and labor shortages. For example, a matching of job ads with bias dictionaries allows for predicting effects on reactions to job ads and application outcomes of job ads.
Overall, online job ad analysis can be a valuable tool for job seekers, employers, and researchers looking to understand the job market and make informed decisions about their career or recruitment efforts.

What Are the General Limitations of Online Job Ads?

While an important tool to get insights into the labor market, OJAs have several limitations:
  • Bias: OJAs do not represent the labor market at large as they only capture positions that are advertised online. Many open positions are not published online and on the other hand, job seekers might not only look online for postings. The factors that determine which jobs get published might vary depending on the industry, organization size, etc.
  • Incomplete Information: OJAs can only provide a summary of tasks and responsibilities for a position and therefore often provide an incomplete list of the qualifications actually required.
  • Duplication: As positions are often advertised on multiple platforms or websites at the same time, it makes it difficult to get an accurate estimate of how many unique job postings there are at a given time.
  • Expiration of job postings: Job postings sometimes remain active on job portals even though the position is already filled. Furthermore, there are several challenges involved in collecting data continuously to identify when exactly a job posting was deactivated. This further complicates the issue.
  • Misleading language: Job postings are written in order to attract potential candidates and meet legal requirements. This can result in misleading language and makes it more difficult to accurately capture the qualifications required.
Some of these limitations can be mitigated and are described in Overview - Challenges, but some limitations are inherent to any analysis of OJA data.
Note that employers do not disclose all aspects of a given job in the job ad. For instance, Stops et al. (2021, p. 21) assume that employers include information like skill requirements explicitly in situations when these employers consider them to be essential for carrying out the activities in the job they offer. They also mention further criteria for including information in job ads. They conclude that, though job ads rarely represent complete job profiles, this information is highly relevant for the recruitment of workers for the respective job.
Michael Stops (IAB)
Last modified 6mo ago