The brief Wikipedia article on IPA suggests 1-15; this is a good starting-point; (remember of course, that, because of its nature as an information platform, Wikipedia cannot be used as an academic reference----but it is very useful all the same).

In qualitative research one should continue data collection until saturation  has been reached. To this end it is important to carefully determine who your interviewees are (i.e. Purposeful sampling). To be able to reach saturation one should perform data collection and data analysis iteratively. Often the number if interviews is between 12-20.  Of course, it also depends of whether one is able to find enough interviewees: in some areas people might be reluctant.

I found this book helpful

Cresswell: qualitative inquiry and research design: choosing among five traditions.SAGE, 1998.

Success with your research!

In qualitative research there is not a predetermined sample size. The sampling is started with purposive sampling by selecting the key informants. Then you analysis the data and decide to select other participants. Also it depends on the researcher skill. An expert researcher may reach to data saturation with 10 participants but the novice researcher with 20 participants.

Good luck

The below papers should be helpful to your topic. A focus on the quality of research results/contributions is more important than the quantity. 

• Guest, G., Bunce, A. and Johnson, L. (2006) How Many Interviews Are Enough?: An Experiment with Data Saturation and Variability, Field Methods, 18, 1, pp. 59-82.
• Lester, S. (1999). An introduction to phenomenological research, from Taunton UK, Stan Lester Developments: www.sld.demon.co.uk/resmethy.pdf
• Marshall, B., Cardon, P., Poddar, A. and Fontenot, R. (2013) Does sample size matter in qualitative research?: A review of qualitative interviews in IS research, Journal of Computer Information Systems, 54, 1, pp. 11-22.
• Mason, M. (2010) Sample Size and Saturation in PhD Studies Using Qualitative Interviews, Forum, Qualitative Social Research, 11, 3, pp. 1-20.
• Pietkiewicz, I. and Smith, J. A. (2014) A practical guide to using Interpretative Phenomenological Analysis in qualitative research psychology, Psychological Journal, 20, 1, pp. 7-14.
• Starks, H. and Trinidad, S. B. (2007) Choose Your Method - A Comparison of Phenomenology, Discourse Analysis, and Grounded Theory, Qualitative Health Research, 17, 10, pp. 1372-1380. 

I am most grateful and appreciative of these thoroughly helpful answers, references, and brilliant discourses on saturation vs. sample size.  

As Margaretha H. Sagasser said we can considere saturation for qualitative research. 

It's better to continue data collection and interviews (in general between 15 to 20 / 25) until saturation  

page 22 in this 

https://www.rds-yh.nihr.ac.uk/wp-content/uploads/2013/05/5_Introduction-to-qualitative-research-2009.pdf

Good luck 

 Hi Russell:  Thanks, the 8-10 figure is what I originally thought, and it's helpful that you corroborated my original opinion.  But, it appears as if there are many perspectives about this number, some going up to 20 or 25, or saturation as the guide.  They all seem helpful.  I haven't read the recommended articles yet, but will balance out scope as I discern more about IPA.

Ava

Sample size dependes several factors, but  8-10 is ok.

The more the better, obviously - quantity eventually equals quality (assuming the interviewees are somewhat qualified) - as long as you have the time and energy to invest in more interviews. It's hard to recommend an average number without an in-depth meta-analysis of previous studies; but for the sake of avoiding vagueness, 8-10 should suffice. Make sure the interviewees are quality, that is, that they meet the criteria you see most relevant, and it should make up for any reprimand around saturation.

Ava, several others have already told you,  the key to knowing "how many" is when you reach saturation. If you keep looking for a specific number in lieu of reaching saturation, your study may not be very trustworthy. 

Agree with Susan; my previous contribution was just to suggest a non-committal parameter for 'getting started'.

Dear Ava

The golden rule in qualitative sampling is to continue incorporating new interviewees until you reach the "saturation point". That is until you don´d find new categories or new themes related to your research problem. So after an initial sampling you must start the data analysis and decide if you continue to expand the sample. Obviously the deeper and longer your interviews, the saturation will come sooner. For budget and time purposes, I would recommend that you tentatively estimate to do 25 interviews. Good luck in your research.

Regards,

Jorge

Thank you, everyone; the idea of the saturation point seems more important than I originally realized.  I will consider the various scopes suggested.  The suggestion to start the analysis earlier and decide on an ongoing basis if I continue to expand the sampling is helpful. 

In my view IPA has a big focus on data richness, so it maybe that as little as five participants may be enough over the course of the research. However you should carry on until you research Data saturation.

https://researcholic.wordpress.com/2015/03/20/sample_size_interviews/

The question is about an IPA study which does not advocate saturation. A smaller sample size (usually 6-8) is highly recommended for an IPA study to achieve rich phenomenological insight. However its not uncommon for an IPA study to a larger sample (10-15). nonetheless, data saturation is never an objective in an IPA research

Thanks for the newest post on this issue of question size for IPA, Muhammad and Abdul.  I have looked into each of the answers, weighed and balanced them, checked several texts, and made a recommendation to my oral comprehensives board about a month ago.  One agreed with my recommendation of 4; another felt it was too small; I have gone to 8 for the dissertation at this time with hopes to complete 6.  Also, I intend to do three research events per participant so in actuality, my 6-8 completion is for a more longitudinal IPA approach which is seen in the literature.

warm regards,

Ava

Jonathon Smith, who invented IPA, provides a useful discussion about numbers of participants in this article. His definitive answer is, btw, that there's no definitve answer :)

https://www.researchgate.net/file.PostFileLoader.html?id=53c8b90acf57d7ce4b8b45a2&assetKey=AS%3A273565755084817%401442234566451

The truth of so many of your answers to my (somewhat naive) 2016 question asking how many participants are ideally part of an IPA qualitative study has become self-evident in my current, live, phenomenological dissertation fieldwork involving semi-structured interviews. To write the proposal of the dissertation, I had to specify a certain amount of interviews within my dissertation methodology section, summarizing multiple sources and experts' opinions. I specified eight interviews with two interviews per person after a moratorium of typing up transcripts and reviewing them. However, within the actual fieldwork which has been ongoing between May and up through September 2019, I have learned that there are no definitive answers, as was stated by many question-answerers as well as works on IPA. As I am doing the interviewing, assessing what I am learning, asking new questions, delving into multiple layers of psychological insight, analyzing somewhat as I'm going on, I am doing more than eight participants. I am up to about 14 now, some of the last of which will only be one interview each. Also, I am discovering new participants who help me flesh out parts of the fieldwork research that are not yet answered by the original eight. So, yes and no, there are no definitive answers to how many IPA interviews are ideal for a study. All those who wrote about paying more attention to saturation of data and insight were correct, as I'm learning on a daily basis.

Hi there,

I think the key thing in IPA is that you want to be able to retain an individual focus as well as focusing across the experiences of the group. Sample sizes are typically small (e.g. 5-6) as richness and depth are key. The sample should be homogenous so that you can draw on shared experiences across the group. The concept of data saturation in qualitative research is only relevant when doing a grounded theory analysis and is not a concept that should be applied to any other type of qualitative methodology, despite it being talked about widely as one can see in this thread. It is deemed relevant in grounded theory as one is trying to ensure that all relevant issues are identified for theory development. It is of course a slightly erroneous idea even here as the next person may well say something different. Instead in general qualitative research we are interested in exploring meaning for specific people in a specific time culture and place. Thus 'saturation' is not required.

Hope this is helpful.

Hi Jane: Thank you for your answer, which I find fascinating. Even though my dissertation is now done and waiting final approval before the defense, in the course of fieldwork, I did find that saturation of data led me to the insights I was seeking. There were many twists and turns related to scope, starting from the idea of data richness in the diss proposal with 3-8 participants and then what turned into 20 participants in the actual fieldwork, as I continued to recruit when the insights and findings seemed thin; these 20 were spread evenly throughout the country of Ecuador, by gender, by age, by age at time of expatriation, by length of expatriation, and by professions pre and post-expatriation. Here is an excerpt from my dissertation on the idea of scope:

Scope Considerations

There existed differing perspectives within the literature on the ideal scope for IPA and general qualitative studies. Smith et al. (2009) stated that IPA studies tended to be conducted with relatively small sample sizes with an aim to seek a “reasonably homogeneous sample” (p. 3) so that convergence and divergence of insights about a topic may be explored in detail. They suggested that a comprehensive study could be conducted with as few as three to eight participants, citing considerable success with one or two thoroughly researched cases; they also discussed larger IPA studies. However, Morse (2015) wrote, in terms of general qualitative sampling not specific to IPA, that it was difficult, in advance, to predetermine the size of the final sample:

The short answer is that trying to predetermine sample size is a futile task. But, we do know that if the sample is too small, data are not saturated, the results obtained are superficial and obvious, and cherry picking occurs in the data. Data will be difficult to analyze, because the categories will not be evident, and theorizing will be difficult if not impossible. . . . the researcher will be uncertain about the findings…nothing of interest to write up. The results will be predictable and easily predetermined. (Morse, 2015, p. 3)

Morse suggested, to consider for the initial part of the fieldwork, two levels of participants; first, a “convenience sample, interviewing everyone who volunteers,” could be, second, changed to “theoretical sampling” (p. 3) to gain “information from those most likely to know the information required to verify or to move understanding forward” (p. 3). A PhD research blog recommended 12 interviews for qualitative research:

Data saturation can occur within the first twelve interviews and after that very few new phenomena are likely to emerge…when undertaking research that is reliant on a phenomenological approach, the sample size is usually driven by the need to uncover all the main variants within the approach…within conditions such as this, small survey samples of less than twenty are common. Finally the view of Creswell (2011) in relation to sample size is that normally within qualitative research, it is typical “to study a few individuals or a few cases” (p. 209). (Researcholic, 2015)

For some phenomenological research, which IPA is inclusive of, multiple events per each individual participant were recommended by Marshall and Rossman (2011)—three in-depth interviews per participant in a sample. They did not discuss total scope:

The first focuses on past experience with the phenomenon of interest; the second focuses on present experience; and the third joins these two narratives to describe the individual’s essential experience with the phenomenon. Prior to interviewing, however, the research using this method may have written a full description of his own experience, thereby bracketing off his experiences from those of the interview partners. This phase of the inquiry is referred to as epoché…to permit the researcher to gain clarity from his own preconceptions. (p. 148)

Although, originally, three interviews per SIE was an ideal considered in my early design, several PhD advisors’ counsel was against it for fieldwork in Ecuador. Given the exigencies of travel, daily life, and the shifting availability of SIEs who lived in multiple regions of a less developed Andean country, multiple interviews might be overly labor intensive to conduct, transcribe, and analyze; as importantly, three research events would involve too much commitment on the part of participants and they or I might not be able to complete this scope successfully given the vagaries of movement inside Ecuador.

Other academicians experienced in IPA recommended saturation of data should be the core determinant of number of interviews. This implied that I would keep conducting SIE interviews until research results seemed saturated, until insights repeated, and when no new information was forthcoming. Keeping saturation in mind instead of a specific scope was the prevailing theme in answers to a question I placed on ResearchGate, an online forum for academic/university qualitative researchers around the world. I received about 18 answers between 2017 and 2019 in regard to my question—how many interviews does a typical IPA study involve? Most researchers referenced the concept of saturation and responded in this way: “The key to knowing ‘how many’ is when you reach saturation. If you keep looking for a specific number in lieu of reaching saturation, your study may not be very trustworthy.” “The golden rule in qualitative sampling is to continue incorporating new interviewees until you reach the saturation point…until you don´t find new categories or new themes related to your research problem.” “In my view, IPA has a big focus on data richness. . . . however, you should carry on until you reach data saturation” (ResearchGate, n.d.).

Morse (2015) discussed how rigor, quality, and reliability in interviewing strategies could be ensured with more time and length. To obtain better data qualitatively:

Prolonged engagement and persistent observation are both necessary for producing thick, rich data. The assumption underlying these criteria is that spending more time on data collection in a particular setting provides time for trust to be established with participants. With increased trust (and intimacy), you will get better, richer data. (p. 3)

So, this is going on too long, but scope and data saturation remain a topic of great interest to me, and I recommend that a) theoretical issues should first be considered in scope, but b) within fieldwork it might be necessary to go for more participants than originally suggested to gain greater qualitative confidence in the data.

Thanks for the ideas, Jane.

Smith et al. (2009) posit that there is "no right answer to the question of sample size" in IPA (p. 51). They do advise 3-6 participants for a student project. Some responded here mentioning data saturation. It is worth noting that saturation is typically not a process in IPA data collection and analysis, according to Brocki and Weardon (2006).

Brocki, J. M., & Wearden, A. J. (2006). A critical evaluation of the use of interpretative phenomenological analysis (IPA) in health psychology. Psychology & Health, 21, 87-108. doi:10.1080/14768320500230185

Smith, J. A., Flowers, P., & Larkin, M. (2009). Interpretative phenomenological analysis: Theory, method, and research. SAGE

I rechecked the Smith, Flowers, & Larkin (2009) book on Interpretative phenomenological analysis after Dr. Patton's commentary on potentially a smaller sample size for student projects. I thought I had practically memorized this section in this bible of IPA, while trying to figure out scope for my doctorate fieldwork. First, however, let's say that student projects could be divided into undergraduate, masters, and PhD. Smaller scope of 3-6 makes sense for undergraduate and masters, especially when there is less experience and when many layers of analysis will be done. Essentially, the IPA researcher is using analysis to go deeper and deeper, rather than a larger scope to go sideways. For my doctoral fieldwork, I needed a varied representation-- men and women, older and younger, U.S, Canadian, and Western European, representation of marital status, ethnicity, and profession, length of time in expatriation, as well as finding participants from six different regions country in South America, whose participants seemed to reflect the variance of location/place. Smith, Flowers, & Larkins (2009) then stated that, for doctoral fieldwork, "we often think of a PhD as being made up of three self-contained but related studies. . . the first study to be a single case study, the second to offer a detailed examination of three cases, and the third to examine a larger sample of eight participants from a different location" . . . or a "bolder design" of "multi-perspectival studies" (p. 52); thus, there is some latitude. I submit with these IPA authors that the subject of sample size in IPA is a tantalizing one for qualitative researchers and there is always the careful weighing of the dilemma of depth vs. quantity. Overall, IPA scope recommendations seem to side with deeper layering of analysis using smaller samples as indicated by Dr. Patton in the previous response.

6 might be enough, all you have to do is make sure that you draft well your objectives as you derive your interview questions to ensure that everything is covered and well detailed.

IPA would be a fantastic methodology to research your topic. Very important to construct your questions to allow participants talk elaborate on their immigrant lived experience. There would be no harm in interviewing 10-15 people for your dissertation because some people may give you very cut and dry answers. As a novice researcher, there is always the concern with the interviewing skill. The question here is also that of how much time you can set aside to analyze the richness and depth of all interviews and do you allow 60-90 min or more for these research conversations. Oftentimes, telling participants that the interview will last 90 min or more is a death wish to your recruitment as people are busy and nobody wants to spend 1.5 hr or more on being interviewed. People may also feel intimidated by the amount of time they would need to devote to the interview.