As you move from one category of information to another, it may be necessary to alert respondents to the change in the topic of conversation. This will help them clear their minds from the previous set of questions and avoid what I call “order misunderstanding.” Order misunderstanding is when respondents misunderstand a question because they bring forward the parameters of the previous question or set of questions.
For example, after asking a series of questions about the entire family, let’s assume you want to ask a set of questions about only the person taking the survey. Add the following transition statement to the questionnaire:
Now we are going to ask a few questions about you personally.
This will help ensure that respondents do not carry forward a family-oriented mindset from the previous sequence of questions.
Another situation that might benefit from a transition statement is moving from asking about past behavior to asking about future behavior. You might add the phrase:
Now we are going to ask some questions about what you might or might not do in the future.
Another example comes from employee engagement and retention surveys. After asking a number of questions about the company, the questionnaire might move to a series of questions about the department where the employees work. A transition statement like this would help ensure that respondents know that the focus of the questions has changed:
We now need to ask you a few questions about your department.
Transition statements like these help respondents shift their focus from the previous set of questions to a new set of questions. The result will be more accurate answers.

(This guideline is one of 65 guidelines from my book, The Complete Guide to Writing Questionnaires: How to Get Better Information for Better Decisions, p. 58.)