In other cases, the survey sample is taken directly from a company s client database, if available. With a mail survey however, it can be difficult to control the sample in a mail survey. Addresses can be inaccurate, and anyone in the household can fill out the survey even if they are not who the survey was intended for. Careful attention must be paid to the survey responses that are received. Often, the survey sample is biased because the people who take the time to fill out and return the survey are not indicative of the entire population.
Returns are frequently skewed to older people who are home during the day.
The response rate is low in mail surveys, therefore more surveys need to be sent out to reach the required sample size. Generally, mail surveys are slow to complete and survey response rates can be affected by the seasons. For example, fewer people respond in November and December, when they may be busy preparing for the holidays or in the summer when they may be on vacation. Mail surveys can be successfully used in the workplace for obtaining anonymous feedback from employees. They also work well in service industries where management wants to conduct an ongoing measurement of the quality of service provided.