Survey and focus group is different with one another. Survey is quantitative while focus group is qualitative. In comparison in the weakness for survey and focus group is that sometimes the respondents may not give precise and honest answers which can may lead to misrepresentation in analyzing the data.
This is same as focus group in which huge amount of data may lead to misrepresentation from different opinions of the group. Another same weaknesses of focus group and survey is, it is very difficult to control in term of collecting data because it needed a lot of time in analyzing and finalizing in order to get a better result of market research. Survey can be in disadvantages because some responders tends to have difficulties in providing answers that are uncomfortable to themselves regarding on the questions. As for focus group it need full agreement from the team but it is difficult to have full agreement which may leading the results to be biased hence it is difficulty to have same ideas or opinions in the same room.