Each sampling method suffers from a form of bias. Identify the bias, tell how the sample statistic might differ significantly from the population parameter, and (writing to learn) suggest how the problem might be corrected.
To assess consumer response to its new cereal flavor, a cereal company passes out free samples at a local mall and offers shoppers a $\$ 5.00$ gift certificate if they will fill out a brief form evaluating the new product. They find that 94$\%$ of the respondents like the new flavor.