The market research studies conducted through questionnaires that are served to respondents using the Internet are called online surveys. Information about these surveys is generally given to the respondents via email and the surveys are to be completed in an online environment.

Opt-in refers to a way of seeking and obtaining permission from the participants for contacting them again in future for various purposes. There is also “double opt-in” which is a process where the consumers sign-up online for a certain service and then they are sent an email to which they respond, thus agreeing to the services offered by the company twice.

In an experiment the accepted value given for a single instance of a sample study is called an observation.

Observation Research is an experiment conducted without any direct interaction between the investigators and the respondents. These are also known as quasi-experiments.

Observation room is the ante room generally separated from the main room where the participants or subjects of a study are seated. This is usually separated from the main room by a one-way mirror allowing the investigators to observe the reactions and hear what is going on during a focus group. Observation room is also called the back room or the viewing room.

Omnibus panels are the panels where studies are conducted in intervals. This allows several companies to purchase a few questions on a single survey and those are administered to a very large audience. The survey results for each question are delivered to the company, which posted that particular question as well as the rest of the surveyed demographic information. This is also known as a piggyback survey because many companies can ride side by side on one survey.

The impact that a particular program creates after it has gone on air is known as the on-air testing.

One-Group Pre-Test Post-Test Design is a design developed before the experiment wherein measurements are taken before and after the test to note the differences. Here control group is not used.

This is a qualitative research technique of interviewing where just the moderator and a single respondent are present.

One-way frequency table is a way of charting how often particular responses are used for each question on a survey.

One-way mirror is a special mirror that feels like a mirror from one side and like a plate of glass from the other side. This mirror is used so that observations can be made discreetly from a room, which is separated from the room wherein participants are seated and a study is in progress. This mirror allows the researchers to view the subjects, but the subjects only see themselves through the mirror when looking at the same piece of glass. Most focus groups are conducted in rooms separated from an observing room by a one-way mirror.

OpenSurvey is used in organizations promoting open standards in market research.

Opt-Out is an option that the respondents can exercise if they do not wish for the company to contact them for any reason, usually the reason of market research. This opt-out option can be exercised through a system set up so that people can no longer be contacted by the company.

Optical Character Reader (OCR) is a computer program that is able to scan printed characters and translate these codes into electronic data.