Sample size in qualitative interview studies: guided by information power

Kirsti Malterud; Volkert Dirk Siersma; Ann Dorrit Kristiane Guassora

doi:10.1177/1049732315617444

Sample size in qualitative interview studies: guided by information power

Kirsti Malterud, Volkert Dirk Siersma, Ann Dorrit Kristiane Guassora

1238 Citations (Scopus)

Abstract

Sample sizes must be ascertained in qualitative studies like in quantitative studies but not by the same means. The prevailing concept for sample size in qualitative studies is “saturation.” Saturation is closely tied to a specific methodology, and the term is inconsistently applied. We propose the concept “information power” to guide adequate sample size for qualitative studies. Information power indicates that the more information the sample holds, relevant for the actual study, the lower amount of participants is needed. We suggest that the size of a sample with sufficient information power depends on (a) the aim of the study, (b) sample specificity, (c) use of established theory, (d) quality of dialogue, and (e) analysis strategy. We present a model where these elements of information and their relevant dimensions are related to information power. Application of this model in the planning and during data collection of a qualitative study is discussed.

Original language	English
Journal	Qualitative Health Research
Volume	26
Issue number	13
Pages (from-to)	1753-1760
Number of pages	8
ISSN	1049-7323
DOIs	https://doi.org/10.1177/1049732315617444
Publication status	Published - 1 Nov 2016

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title = "Sample size in qualitative interview studies: guided by information power",

abstract = "Sample sizes must be ascertained in qualitative studies like in quantitative studies but not by the same means. The prevailing concept for sample size in qualitative studies is “saturation.” Saturation is closely tied to a specific methodology, and the term is inconsistently applied. We propose the concept “information power” to guide adequate sample size for qualitative studies. Information power indicates that the more information the sample holds, relevant for the actual study, the lower amount of participants is needed. We suggest that the size of a sample with sufficient information power depends on (a) the aim of the study, (b) sample specificity, (c) use of established theory, (d) quality of dialogue, and (e) analysis strategy. We present a model where these elements of information and their relevant dimensions are related to information power. Application of this model in the planning and during data collection of a qualitative study is discussed.",

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AU - Malterud, Kirsti

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AU - Guassora, Ann Dorrit Kristiane

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Sample size in qualitative interview studies: guided by information power

Abstract

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