I don't think there's any rule of thumb regarding that. However, you might want to look for previous studies regarding what you are working on...as a justification for how many interviews you should use. 

Some researchers recommend theoretical saturation - you continue sampling until you are getting no new information but this can be problematic. In general my experience is that a relatively small number of respondents provides detailed and rich information. Often we interview more informants  than is necessary and have difficulty handling a large amount of  complex data.

The first thing to do is to think about the different groups that you need to include in your sample that previous research (or logic) suggest may be different. Men and women, different age groups, people living in urban and rural areas, different economic groups  etc. Once you have identified the different groups you then need to think about how many to interview from each group. I would suggest at least three or four.

Cost and time are other criteria you will need to take into account.

When I conducted my qualitative research I opted to interview 2 people with around 15 questions in my questionnaire. However, you can chose to do more if you wish to get a richer quality of information. It will be important that you have sufficient time to spend coding your interviews afterwards to look for core threads or themes that appear in the answers. If you have NVIVO or some other programme to do this for you and you don't need to do it manually then you could distribute 10 or more questionnaires. You will need to take into account the time available to you and the deadline for the completion of your piece of work. the programmes you have at your disposal for coding before making a decision on the number of one to one interviews that you wish to hold.

I propose to continue sampling until you are getting no new information, however this methodological approach must be backed up by employing few different fieldwork tools, e.g., semi-structured interviews, in-depth interviews and mental maps - such that you make sure that no information was missed / all information was revealed.

You might find this blog post helpful: https://researcholic.wordpress.com/2015/03/20/how-many-people-shall-i-interview/

They advocate 20-22 in that article.

Different researchers have developed their own writing styles, as well as approach to investigation, and, what worked for one investigation at a time may not work for another. Therefore, researchers must be dynamic in the field. The issue in question might be such that you would have to target target certain persons/ respondents. A crowd may not be useful. Once you are able to get respondents from different cadres of people and professions as may be demanded by the study’s expected objectives, you would know how well you have done in the work. The relevance of the respondents and their responses matter. I would submit by saying that you must make sure that your questions are articulately coined in such a way that they would thoroughly address the stated objectives.

Number of respondents to be interviewed normally depends on the point of saturation regardless of the numbers that you want to interview. If you find that your respondents are not giving you any new information, then it is tell tale for you to stop. However, with regards to the number of questions to be asked, it depends on how rich the data that you want to collect taking into account the resources that you have ie. time, money and etc. What you have to be mindful is that there might be emerging questions that consistently come out from the respondents even though it is not something that you want to ask in the first place. This could give a clue that there is new information that you need to explore further and might give some interesting insight to the issue that you are studying.

Solo una. De ella pueden desprenderse millones.  Para que haya sentido, racionalidad lsentido, no puede haber más que una.  P. Ejemplo.  Marx: como se explica la ganancia capitalista.  Rousseau:  Como consstruir un sistema político que tome a los hombres tal cual son y las leyes cumo pueden ser?.  Freud, que está en el fondo de la histeria?,  Newton, Omo se explica la caida de los cuerpos?.  Ninguna de estas cuestiones tuvo una respuesta única.  Pero si hay muchas respuestas estas necesariamente deben estar formuladas por toneladas de razones...¡eso es ciencia¡ 

I have minimal experience with interviewing, but the times I have done it we used about one page of questions (double spaced).  Don't forget that while you will come up with a list of predetermined questions, you can also ask probing, or follow-up, questions to those answers, as well.  Good luck on your research!

Although there is not any rule, I prefer only a few of questions (max. 3). You need to simplify your research. I hope you find useful this response

The number of questions depends on the research being conducted, the cohort you are interviewing, age etc, Perhaps focus groups may help also. I would suggest as much emphasis should be placed on any ethical issues surrounding the construction of how ever many questions you intend to ask.

The number of questions is no issue per se. Applying a method like conversational analysis (following Sacks) you can analyze one answer, one utterance by one respondent. Saturation and purposeful sampling give criteria on what is possible with regard to a specific study.

The design depends of the number of questions implicit in your research objectives and inicial hypothesis that you want response. The characteristics of the sample is more related to the provision of the differences between discurses that may occur among subjects you study. For this reason the discurse saturation can be a good indicator to finish. 

The focus of the design is the heterogeneity of discurse that can produce the subject. The relationship between discursive heterogeneity and complex social context that will allow you to understand your subject of study. 

You must discover your research needs and modify the design when you consider that there are questions that remain unanswered. It´s an open process.

I think it depend on what you are researching, your research focus and area. However, I would recommend you read Bourdieu (1973) text on 'interpretative method of anthropology'. this literature  is a seminar  text on how to study, analyse, interpret and present ethnographic report.

All the best.

There is no specific number of questions needed. Very often we begin asking questions according to main themes and proceed from  there via probing until we reach saturated point whereby no more new information given by the informants. Also, you need to ask yourself whether you have gauged enough information to answer your research objectives.

how many does your audience expect? why are they reading? what are you sharing? what is the point? you might question is the point of survey representative?   IMO its about how much information you can digests, and from that digestion what is relevant to share for what you are trying to communicate. IMO the most important thing is why does it matter? 

There is no specific number of question needed. We needed the Status Questiones to answer our research

In my opinion, quantitative research is more reliable that qualitative research, however, if you are performing interviews (1 on 1) or using participant observation, this may not be possible. Nonetheless, qualitative research can be as effective as quantitative research if done correctly.Sociologically, there is a research model that is used, with clearly defined steps: 1) selecting a topic 2) defining the problem 3) reviewing the literature 4) formulating a hypothesis 5) CHOOSING A RESEARCH METHOD 6) collecting the data 7) analyzing the results, and 8) sharing the results. A research design is then chosen, then selecting a sample is very important.  You will have to narrow down your population. A target group is selected. Next, you must select a sample.The best way to do this is to use a random sample, in which everyone in the target population has the same chance of being included in the study. Good luck!

I recall hearing an interview with one of the best interviewers of the 20th century, Studs Terkel.  In it, he said that the best interviews were those that posed the fewest questions by the interviewer.  Paying attention and listening mindfully to the story of the interviewee: isn't that what it's all about? 

This has probably been well answered so I will simply put in a short answer.

There are several different ways of developing the inquiry. However, as a general rule which I have found helpful, is that qualitative inquiries involve two specific stages- the first is the point in the process where you have noted specific themes re-occurring. Typically this shapes the inquiry into the second phase, this is where you begin to see a general saturation of those themes in the answers generated in your inquiry.

Obviously there are far more specific methodological nuances that can be looked up in any book on qualitative methodology. Sample size will depend on which method you choose however, the general rule for qualitative inquiry is when you keep getting the same general patterns of answers, you have reached the place you want to be. This can be anywhere from 1 subject in case studies, to 20-30 in phenomenological and other approaches, and sometimes more.  

Good Luck!

I endorse the above statement. I add just a 2cts, using participant observation as a technique increasing the volume of primary data caught in direct interviewing. There is room for more questioning equivalent to interviews, emerging from taking part in an activity.

I want to thank you all for sharing me  your valuable knowledge and experience!

accessible informants should be enough. A plethora of data could be dug via a limited number of question in qualitative studies.

Sorry. As for my previous comment, I would like to change accessible to Accessible and question to questions .

this actually depends with what you are looking for. There is no rule to determine the number of questions all depends with the researcher

Less questions but that can capture all information that you wanted. Eg. having a grand tour question.

Qualitative research is open-ended and flexible. So it will be very difficult to determine the number of research questions ahead of data collection. What usually I do is, with the help of a few guiding questions I start the interview and go on until it reaches the point of saturation.

According to Creswell, W. & Creswell, D. (2019), The total number of questions should be between 5 to 10.

References:

Creswell, W. J., & Creswell, D. J (2018). Research design: Qualitative, quantitative, and mixed methods approach. Sage publications.

Thank you for your contributions like am greatful.

There is no defined methods, the number of questions depends on the investigators until you find the researchers objective but qualitative questions must be broad and based on your research questions and objectives

The number of questions might not really matter as it increases the amount of in-depth information about the subject matter, however one must be cognizant of the interviewees' time and comfort. It shouldn't turn into a nightmare for the informant.

In my opinion, in a thesis writing, the number of research questions will tally with the number of objectives. Not sure, is this practical or not.

Agreed with Jon Hans Wasswa since the main research in a qualitative study is to look in-depth at your research answer. Need to have some ground theories as well.