Representativeness: Less than 60% of the UK population has access to the internet. Attitudes and opinions of online audiences differ significantly from those without internet access, for many subjects, so researchers need to be extremely careful when predicting general public opinion from online samples. The UK online population is skewed towards younger age groups and male respondents. This is less of a problem in the US and parts of Northern Europe where internet penetration is higher.

Availability and quality of sample: No simple database of email addresses exists, so online research is most often conducted amongst online panels of client databases. Client supplied sample can be very unreliable with many old or incorrect email addresses. This will greatly reduce response rates.

Panel research is only conducted amongst those who opt-in to research, so we need to be sure their responses are genuine.

Quality of recruitment and running of the panel needs to be closely monitored.

Verification of respondents: As with traditional forms of self-completion data collection, it is difficult to be sure that your respondent is who they say they are. The 'professional panellist' will try to complete surveys for incentives, so as researchers we need to add verification questions into our surveys and keep the level of incentives under control.