An experimental design involving groups of respondents. Neither group is measured before the experiment. During the experiment the control group is not subjected to the experimental variable. At the conclusion of the experiment, both groups are measured. The control group’s measurement is deducted from the other group’s measurement. This can be easily coordinated using Discuss.io’s platform new feature called the An in-depth conversation with interviewers at the conclusion of a study. The interviewer plays back his/her impressions of the respondent’s feelings about specific questions. This technique is often used immediately after a pre-test of a questionnaire. The information provides the researcher with insights necessary to revise or refine the final questionnaire and/or future studies.respondent hub. The respondent hub allows you to hold sessions with respondents at ease for such experiments.