Panel Samples

Panel Samples

Panel samples are frequently used in marketing research. In panel samples, the same units or elements are measured on subsequent occasions. To give an example: Suppose that one is interested in knowing the change in the consumption pattern of households. A sample of households is drawn. These households are contacted to gather information on the pattern of consumption, subsequently, say after a period of six months, the same households are approached once again and the necessary information on their consumption is obtained. A comparison of the results of the two sets of data would indicate whether there has been any change, and, if so, to what extent. In fact, the information is collected on a more or less continuous basis with the help of panel samples.

Panel samples are extremely convenient and economical and the cost of drawing a second sample is not incurred. But the main limitation of such samples is that it may be difficult to sustain the interest of individuals included in the panel for a long period. Many respondents on the panel may refuse to be interviewed twice or may give poor answers. In either case the quality of the survey will suffer. Another limiting factor in panel samples is that there may be bias on account of the continued participation in the panel. It is felt that the individual is conditioned to some extent by the fact that data on purchases are reported. In such a case the purchase behavior of panel members may become different from others not covered by the panel. Furthermore, panel samples may turn out to be more expensive while locating the same sample of respondents after a lapse of, say, a year, when some of them might have migrated to other areas. This would involve travel costs in addition to being difficult.