Longitudinal analysis

A custom panel or a syndicated panel enables us to monitor the reactions or behaviour of the same person, household or business respondent over a period of time. The panel approach makes it possible to get a continuing series of reports from the same people.

Where one-off studies are used, the researcher may encounter people who are not consistent users of the brand in question. Researchers might then question them about their inconsistent patterns of purchase. However, the panel method gives an opportunity to ask the question at the time the purchase behaviour has changed and to obtain a current and immediate reply rather than one that is dependent on memory.


(Measured in first wave)

End of End of first month second month

Total panel members

Total exposed to early advertising

Purchases by total sample

Purchases by those exposed to early advertising

Purchases by those not exposed to early advertising

(6000) (6000) (600) (600) 9.6% 10.8% 15% 18% 9% 10%

Suppose you wanted to ascertain the impact of advertising on purchases. The introduction of a new product in the market might use an advertising blitz concentrated in the first month. On two successive one-shot surveys, done at the end of the first month and again a month later, questions about advertising recall and brand purchase could be asked, with results showing that brand advertising recall for the test product dropped from 10% to 5% in the two sweeps, while brand purchases went from 9.6% to 10.8%.

People would be unlikely to recall whether they were exposed to the blitz advertising, even though they could recall brand purchase within the week. The panel results among 6000 customers are shown in the table. The data show clearly that blitz advertising had a continued impact.

Panels cost less than a comparable series of parallel but separate samples. There is only a one-time basic sampling cost, be it households or stores, and continuing cooperation may also be high. The sample is the most serious limitation of the panel. With consumer panels, annual loss of members can be substantial. Some panel members soon lose interest and others are sometimes so self-conscious about their participation that their behaviour is affected.


Typical of the kind of data provided by this panel are the following. The reports produced refer to the research purchaser's specific products.

For the information purchaser's particular brand, up-to-date data are provided on such things as total households buying the brand, penetration, brand volume, market share, percentage of the volume on offer, average price, purchase occasions per buyer, market volume per buyer. A demographic analysis is provided for all buyers broken down by social class, household size, age of housewife and region. For example, the report might identify the percentage of a firm's plastic products sold to different sizes of households.

A trend report is also produced showing consumer expenditure on specific product items, such as the firm's plastic bags and plastic bags in total. It might also show sales trends through different types of outlet, for example, ASDA, Boots, Gateway, etc.

Online Survey Champion

Online Survey Champion

There are people all over the world trying to find ways to make money online. From stay at home moms looking to make a few extra dollars to college students and entrepreneurs, the allure of making your own hours and working from home or from the local coffee shop is very appealing.

Get My Free Ebook

Post a comment