Answer:
- voluntary response sample
- convenience sample
Explanation:
Any method of sampling can be biased depending on how they are cared out; however, both voluntary response and convenience are almost always biased. This is because in both the sample is not controlled. In voluntary response, there is no way to ensure that the sample will be representative of everyone since it is based on volunteers. Convenience is also biased because the sample is skewed towards whatever is convenient not what is fair and representative.