Further reading on panel sampling from
https://www.surveygizmo.com/resource...online-survey/
Code:
The Drawbacks of Using Panel Respondents as Your Target Audience
The three main drawbacks of using a survey panel are:
Nonprobablity Sampling
Because the respondents are chosen in a nonrandom manner (forum dwellers only),
some members of the population have no chance of being included. This presents the
problem of calculating how well the sample represents the population as a whole.
Data Quality
Since respondents are incentivized to complete a survey, their motives are not
altruistic. Because they may not be vested in your cause or goal, these responses may
be of a lesser data quality.
Duplicate Responses
Sometimes a panel company will not have a large enough pool to draw from for a
particular demographic in which case they will partner with another panel company to
fill the order. If a respondent is signed up with both panels duplicate responses can
occur.
Most panel companies are vested in providing high quality responses since this is vital
for them to keep repeat business. There will however, be some questionable responses.
The key is to choose a reputable company and to take a close look at the data you
get back to weed out the outliers and duplicate responses.