Web-based questionnaires and questionnaires are a crucial method of epidemiology that provide crucial data on the state of public health and illness. They are a standard method of collecting data, which is often less costly and time-consuming than face to-face interviews, mailed questionnaires, or automated telephone menu systems. Questionnaires and Web experiments do not come free of limitations, which must be addressed in order to get reliable and valid results.

A questionnaire may be affected by response bias. This is the tendency of respondents to answer questions based on their opinions rather than the research objectives. The design of a questionnaire may affect responses in a variety of ways. For example the language of the question may affect whether the respondents comprehend the question and interpret it in the same way (reliable) or whether the question is a good indicator of the subject you are interested in (valid) and if they are able to accurately answer (credible).

A lack of engagement with the questions can make respondents less likely to give honest responses. In addition, the absence of incentives or monetary compensation could make it difficult for respondents to take the time to fill out the questionnaire.

Online questionnaires also pose challenges for certain experimental designs, for read what he said example, positioning or reaction time studies. It is difficult to control and measure variables across participants because of the differences in browser settings operating systems, browser settings, and screen sizes.

Finaly, Web-based surveys can only be accessed by people who are keyboard and Internet literate. This excludes a large segment of the population. It is also difficult for Web researchers to provide participants with a report after the experiment window has closed.