Background: Already in its early days, advertising has been shaped by technology, first in the form of new printing technologies, growing affluence, and other factors that enabled mass circulation of newspapers, magazines, and mass audience radio programs. Today, advertising is going through a transformation that is caused by digitalization. The increased amount of mobile, media and digital devices provide organizations with vast data on how consumers feel, behave, and interact around their products. This data presents opportunities to enhance customer experiences, increase loyalty, and extract value. However, research so far has not sufficiently followed the development of the industry. There is a lack in the understanding of how companies can use big data analytics and for which purposes it is used within online display advertising.

Purpose: The purpose of this study is to advance the understanding of the use of big data analytics by exploring the approaches to big data analytics and the reasons why these approaches are used within online display advertising. 

Method: This qualitative study utilizes a multiple-case study approach to investigate big data analytics within online display advertising. Data was collected through semi-structured interviews with companies from the advertising industry and proven experts in the field of big data. The collected data was analyzed by first applying a within-case analysis, followed by a cross-case analysis.

Conclusion: The results of this thesis show that big data analytics have an increasing impact on online display advertising. The analysis of the findings revealed that descriptive, diagnostic, and predictive analytics are commonly used within display advertising. Descriptive analytics is used to sell advertising space via programmatic advertising and to measure the effectiveness of advertising campaigns. Diagnostic analytics is applied when advertising campaigns perform poorly. Finally, predictive analytics is used to develop and improve advertising products, but also to better target and personalize advertisement.