In an industry to have a better insight into the problems of the labourers the psychologists sometimes gets enrolled as one of the employees and participates in their activities like any other employees this is an example of

A. Raw data B. Ungrouped data C. Either A or B D. None of the above

A. Geometric mean B. Arithmetic mean C. Median D. None of the above

A. Parallel-forms reliability B. Equivalent forms reliability C. Comparable forms reliability D. All of the above

A. Case histories B. Tests C. Surveys D. None of the above