When you conduct interviews, you can find out a lot. You collect primarily qualitative data. (There are some tricks to collect quantitative data as well.) Before you start an interview, it is crucial that you have well-defined interview questions. Because you don't ask questions just for fun: respondents have to answer the central question of your research. That is why I am giving you tips on how to design your interview questions as well as possible:

1. 1. Have clearly worded main and sub-questions ready.
   2. Ask questions that connect to your main and sub-questions. To ensure all of them can be answered, mark behind each question which main or sub-question the question connects to.
   3. Put the questions in a logical order that avoids overlap.
   4. Include introductory text in your interview questions. This text should state why participants are being interviewed and how long the interview will take.
   5. Formulate your questions so that the interviewee understands them. You can test this by practicing the protocol with your colleagues. This way, you will also notice if your questions are asked in the proper order.
   6. Make sure to ask your questions objectively. This will prevent biases that will cause the research to produce the wrong answers and will allow for continued questioning during your interview. Prejudice occurs when you ask leading questions such as "Don't you agree?", "Would you...?" or "Is it true that...?".
   7. Make sure there is room to ask more in-depth questions. In-depth questions start with 'why', 'how', 'what' and 'who'. In these questions, you will find the 'gold nuggets' that will provide special insights for your research.
   8. Write a closing text explaining what will be done with the survey results.

   Finally, I would like to inform you that remaining objective during the interview is essential. Your own opinion plays no role in this; make sure the interviewee can tell their own story.

   More tips to prepare for your interview? Then please read my blog '15 tips for a good interview'.

Suppose you want to research a target group of as many as 10,000 people. Do you have to interview all 10,000 people to get the right results? Certainly not; only a part of the research population needs to participate in your research to get representative results. Let me explain what representativeness means and when the results are deemed characteristic.

Representativeness means the degree to which the respondents in a sample group are a good reflection of the target group of your research. Therefore, your research is representative, which means that the conclusion of your research is true for 'everyone' in your research population.

A sample

If you have a research population of 10,000 people, you will ultimately need to interview 400 people to arrive at the opinion of the larger group. This does not mean that you only need to approach 400 people. You have to deal with a response rate. This is the percentage of people who participate in your survey. Your response rate depends on the subject you are researching, how easy and fun it is to participate in your research, and what people get in return. I often use a response rate of 30% because I usually research fun subjects, and I am experienced in making it easy to participate in a survey. I also ask the client for a nice gift for the people who participate in the survey. Tips to increase your response rate

Because not everyone will participate in your survey, you will need to have a larger sample group. If you need 400 respondents and assume a response rate of 30%, you will need to interview a sample group of 400/30%=1,333.

When you conduct a survey, you must keep in mind that the smaller the research population is, the larger the number of respondents will be to arrive at the desired representative results. Sometimes, however, respondents' input is more valuable than the number of participants. In this case, you're referring to qualitative research, and it can be more important to focus on the research results than the representativeness in some cases.

If you want to know how many respondents you need for your research population: go to a sample calculator. These will often immediately tell you how many people you need to approach in your sample.

The range of research methods on offer is enormous, so you can sometimes not see the wood for the trees. That's why I give you a handy overview of different research methods in this blog. With some of the research methods, you will find a link to a blog with more information.

In this overview, I characterize quantitative and qualitative research methods. Would you like to know more about these? In my previous blog, 'When to choose: qualitative research or quantitative research,' you will find information about the difference between these two types of research.

Qualitative Research

• Group discussion: Conversation or discussion with several people about one or more topics.
• Individual interview: Structured or unstructured conversation with one person in which you go into detail about one or more topics.
• Literature Review: Research in which you use research, theories, and information already available (e.g., from a library or on the Internet) based on a problem statement.
• Mystery visitor: Research method in which you use experts who behave as customers or visitors and assess the quality of service or organization.

Quantitative research

• Observing: Observing actual behavior and recording responses.
• Questionnaires: Recording data and opinions of groups of people using a pre-prepared questionnaire. You can have this questionnaire completed digitally or in writing by a large group of people.
• Tear tickets: A research method in which you get a large group of people to answer one question quickly. This can, for example, be done by giving the audience a piece of paper with a statement on it before a show. After the show, the audience can indicate whether they agree or disagree with the statement by making a tear in the piece of paper.
• Existing source research: conducting research using existing datasets of quantitative data that other researchers have already collected. You then use the dataset again to answer a new question.
• Informal conversations: During an informal conversation that is already taking place, you will ask a few specific questions. You record the answers afterward and repeat them to multiple respondents. The respondents are not aware that they are participating in a survey.
• Ten-minute interviews: Short interviews to find out about respondents' experiences, opinions, and motivations. It is stated in advance how long the interview will last. You can use a timer.
• Tracking: following respondents (e.g., visitors to a museum or customers in a store) through a distinct area. This can be done through the Wi-Fi or Bluetooth of their own devices, but also with a device that you give to respondents, with which you follow them.
• Logbook: A document (digital or written) in which you have visitors or participants record events and specific data.