Concept:
Sociological research uses systematic methods to collect and analyze data about society.
Step 1:
Interviews are widely used to gather detailed information directly from respondents.
\[
\text{Interview is a research method}
\]
Step 2:
Participant observation involves observing people while participating in their activities.
\[
\text{Participant observation is a research method}
\]
Step 3:
Questionnaires are structured sets of questions used for collecting data from participants.
\[
\text{Questionnaire is also a research method}
\]
Step 4:
Prediction is an outcome or expectation based on research, not a method of research itself.
\[
\text{Prediction is not a research method}
\]
Step 5:
Hence, the correct answer is Prediction.
\[
\boxed{\text{(2) Prediction}}
\]