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Qualitative methods

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Qualitative methods are used to describe, interpret and understand connections.

Number of units of analysisFew
AssumptionsLess hard-and-fast knowledge about how results are connected
Starting pointNeed for detailed information
FocusActors’ knowledge is central
IntentionConstructing theory


Qualitative data collection methods make it possible to study a specific subject of investigation in detail and in depth. This can also reveal new and unexpected information. This can lead to a deeper understanding of the subject of investigation, but does make it more difficult to make generalisations about matters beyond the subject itself. Qualitative surveys and observations are characterised by an approach that delivers undistorted and comprehensive information and is therefore suitable in all situations in which a differentiated and detailed description of individual opinions and impressions is called for. Qualitative methods are particularly ideal for collecting detailed suggestions for improvement and for discovering causes (for facts such as dissatisfaction).

Data collection

Qualitative data are collected by the following methods:

  • Various forms of interviews (individual conversations, group interviews, focus groups)
  • Analysis of documents

Sample size

There is no unanimity in the literature about the number of conversations that should be conducted. The opinion of what constitutes a suitable sample size varies between a few conversations and about 200 people, although – depending on the questions being investigated – theoretical saturation sets in beyond a certain number of conversations. This means that the gain in terms of knowledge cannot be further increased through additional conversations. The required sample size is in general distinctly smaller than when using quantitative methods. The principles of theoretical sampling apply to the composition of the sample, meaning that the sample should be adapted to the theoretical considerations and the evaluation questions, put together heterogeneously and contain representatives that are as typical of the population as possible.


In qualitative data collection, analysis is carried out using various forms of content analysis. These are based on summarising and gradually reducing the data-set. Important: Data that has been collected qualitatively can also be assessed quantitatively. 

Flexible application of methods; the method is adapted to the subject of investigation and not the other way around.The required qualifications of the people observing or interviewing are really quite high. The quality of the data also to a certain extent depends on these qualifications.
The openness of the method makes it possible to discover new and previously unknown facts.Analysis relatively intensive, especially compared to quantitative methods.
Since the participants have no guidelines, one receives fairly truthful and complete information about the subjective view of the interlocutors.One cannot derive any numerical figures from qualitative data.
The focus is determined by the participants themselves and is therefore directed towards facts that are of relevance to them.
The personal interaction offers the possibility to ask for background information and to clear up uncertainties.
High validity of content through non-predefined approach
More in-depth information through open questioning
Greater subjectivity of results