What are choice weights?
Sampling bias is caused when a specific kind of sub profile in the target respondent is over or under represented. For example, if the study aims at studying women in a developing country, using an Internet survey may result in a biased sample. As the Internet penetration in developing countries is not too high, it might result in a sample that is in favor of high income groups or highly educated women who have adapted to the Internet faster than some of the others.
Survey choice weights allow you to balance the sample and provide results that are more in-line with the true population
Which questions can I weigh?
The only questions that allow choice weights are the multiple-choice single answer.
How can I assign choice weights?
When editing the survey, all your multiple-choice questions will have this button 
at bottom right. After clicking this button, all your choices will appear and
all you have to do is enter a number for the weight of each choice.
Which analyses use the choice weight?
There are currently three analyses that use questions weights: the weighted average, question score, and the weighted question distribution.
