Personal observation is usually more likely to have observation bias than mechanical observation.
Observation Study is a research study where data is collected by watching consumer behaviour or events taking place. Omnibus Study is a periodic study that asks questions on a number of unrelated subjects. The results may be completely or partially syndicated among clients. One Stage Sampling is a sampling procedure that involves collecting data from all available units in selected sub-groups of a population of interest. One-sided Question is a form of leading question that presents only one aspect of an issue being considered by respondents.