You are preparing a market study, a customer satisfaction evaluation, or a university project. The classic reflex: create a form with a few questions and send it by email. The problem is that the choice of questionnaire format directly affects the quality of the collected data. A poor format produces unusable responses, regardless of the number of respondents.
Validated questionnaires or custom questionnaires: a structuring choice
Before writing any questions, a decision must be made. Will you use an existing questionnaire or create one from scratch? This choice has direct consequences on the reliability of your results.
Further reading : Analysis of the best sites to discover current fragrance trends
In public health and social sciences, the recommended practice is to favor standardized and validated questionnaires (such as the PHQ-9, AUDIT, or SF-36) rather than writing your own questions. These tools have been tested on large populations, translated according to strict protocols (back-translation, pre-tests, psychometric validation), and allow for international comparisons.
Item banks like the PhenX Toolkit or the NIH Toolbox facilitate this process. If your study topic already has a validated questionnaire, using it saves you time and enhances the credibility of your conclusions.
Recommended read : Maintenance and Tips to Extend the Lifespan of Your Football Equipment
In marketing or project management, the situation differs. You will often need questions specific to your product or context. Custom creation is then justified, provided you adhere to precise formulation rules. Understanding the types of survey questionnaires helps make this initial decision without fumbling.
Open questions and closed questions: what each format captures
Have you ever filled out a form asking you to rate a service from 1 to 5? That’s a closed question. And a free text field to explain your rating? That’s an open question. The distinction seems simple, but it determines the type of data you will obtain.
Closed questions: easy-to-analyze data
Closed questions offer a predefined choice of answers. They come in several formats:
- Single-choice questions (yes/no, Likert scale) produce quantitative data that can be directly used in statistics
- Multiple-choice questions (checkboxes) allow for identifying combinations of preferences or behaviors
- Ordinal scale questions rank items by priority, useful for understanding respondents’ trade-offs
Closed questions maximize the response rate because they require little effort. They are suitable for large-scale surveys, whether online or by phone.
Open questions: nuance, but high analysis cost
An open question allows the respondent to express themselves freely. It captures qualitative information that no list of choices could anticipate. An unhappy customer will explain a specific problem you hadn’t considered.
The downside: each response must be read, categorized, and sometimes interpreted. In a sample of several hundred people, the processing of open responses can account for the majority of analysis time. Reserve them for questions where you seek to understand a “why,” not to measure a “how much.”
Sample bias and accessibility: the trap of 100% online surveys
Online distribution has become the default mode for most surveys. Quick and inexpensive, it allows reaching a large number of respondents. It also carries a risk that many designers underestimate.
An exclusively online questionnaire excludes certain populations: elderly people with limited access to technology, residents of rural areas with limited digital access, individuals with disabilities if the form is not accessible. This sample bias can skew your conclusions without you noticing.
Current data collection recommendations suggest anticipating these inequalities from the design stage. This means planning for alternative formats (paper version, telephone administration, face-to-face assistance) and training interviewers on the specific biases of each mode.
If your target population is homogeneous and connected (app users, newsletter subscribers), an all-online approach works. As soon as you aim for a broader population, combining multiple distribution modes reduces the risk of bias.
Adapting the questionnaire format to the research objective
Each research objective calls for a different format. The table below summarizes the most common correspondences:
| Objective | Recommended format | Example of use |
|---|---|---|
| Explore a poorly known topic | Open questions, semi-structured interviews | Identify barriers to product adoption |
| Measure an opinion or satisfaction | Likert scale, closed questions | Customer satisfaction survey after purchase |
| Compare groups | Validated standardized questionnaire | Multicentric public health study |
| Test the effect of a variable | Causal survey with a control group | Measure the impact of a price change |
You will notice that the choice is not only about “open or closed.” The research method (exploratory, descriptive, causal) guides the type of questions, the mode of distribution, and the sample size.
An exploratory questionnaire with five open questions sent to twenty well-chosen people will often produce more useful information than a closed survey of thirty questions sent to a thousand unqualified contacts. The relevance of the sample matters more than its size.
The last point to keep in mind: a questionnaire that is too long decreases the completion rate. Limit the number of questions to the strict necessary to meet your objective. If you are unsure whether to add or remove a question, remove it. The data that no one finishes filling out is worthless.