Web-based surveys and questionnaires are an essential method of epidemiology that provide crucial information about the state of public health and disease. They are the most commonly used methods of gathering data, and are often cheaper and less time-consuming than face-toface interviews, mailed questionnaires, or automated phone menu systems. However, questionnaires and Web experiments have a number of limitations that need to be addressed in order to ensure valid and reliable results.
A questionnaire can be affected by response bias. This is the tendency for respondents to answer questions based upon their opinions instead of research goals. Additionally, questionnaire design can influence responses in various ways: for example the wording of questions can influence whether respondents comprehend and interpret the questions in the same way (reliable) and also, determine what you're interested in (valid), or are able to answer accurately (credible).
Lack of engagement with the questions could also cause respondents to be less inclined to provide honest answers. In addition, a lack of incentives or compensation can discourage respondents from taking the time to fill out survey forms.
Online questionnaires can also be difficult for certain research designs, such as studies of reaction times or positioning. The variation in settings for browsers as well as screen sizes and operating systems makes it challenging to measure and control the same variables across all participants.
In addition, Web-based surveys are only available to people who are keyboard and Internet proficient, which currently excludes a significant proportion of the population. Furthermore, it's often hard to Web researchers to debrief participants after an experiment's window closes.