## Abstract

This paper explores the sample size in qualitative research that is required to reach theoretical saturation. I conceptualize a population as consisting of sub-populations that contain different types of information sources that hold a number of codes. Theoretical saturation is reached after all the codes in the population have been observed once in the sample. I delineate three different scenarios to sample information sources: “random chance,” which is based on probability sampling, “minimal information,” which yields at least one new code per sampling step, and “maximum information,” which yields the largest number of new codes per sampling step.

Next, I use simulations to assess the minimum sample size for each scenario for systematically varying hypothetical populations. I show that theoretical saturation is more dependent on the mean probability of observing codes than on the number of codes in a population. Moreover, the minimal and maximal information scenarios are significantly more efficient than random chance, but yield fewer repetitions per code to validate the findings. I formulate seven guidelines for purposive sampling and recommend that researchers follow a minimum information scenario.

Next, I use simulations to assess the minimum sample size for each scenario for systematically varying hypothetical populations. I show that theoretical saturation is more dependent on the mean probability of observing codes than on the number of codes in a population. Moreover, the minimal and maximal information scenarios are significantly more efficient than random chance, but yield fewer repetitions per code to validate the findings. I formulate seven guidelines for purposive sampling and recommend that researchers follow a minimum information scenario.

Original language | English |
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Publisher | Utrecht University |

Pages | 1-25 |

Number of pages | 25 |

Publication status | Published - 2015 |

### Publication series

Name | Innovation Studies Utrecht (ISU) Working Paper Series |
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Publisher | Utrecht University |

No. | 05 |

Volume | 15 |

## Keywords

- qualitative research
- purposive sampling
- theoretical saturation
- sample size
- simulation