Researchers use interviews or questions to ask people about their behavior, attitudes, beliefs, opinions, or intentions.
Psychologists use surveys, conducted in person or online, to collect data on almost anything behavior related and, mental process, from parenting to sexual behavior
Validity of surveys depends party on whether the wording is clear and how questions are phrased.
The way a question is worded can influence a certain answer. If you suggest that someone is more sick due to the weather they may report more symptoms compared to when the weather is not suggested.
Validity also depends on the group being surveyed. It must represent the group be in studied properly.
People may not want to reveal undesirable or embarrassing things about themselves. Or they will say what should be said
In an example, people were asked if they wash their hands after using the bathroom. While the survey said 95 percent said yes, an observed experiment found it close to 67 percent