This design is a variation of the “after-only design”. In this case, rather than selecting the experimental design before the experiment none of the groups is sleeted before the experiment. The groups (equivalent experiment and control) are identified only by the treatment given after they are exposed to the experiment.

Assume, a company wants to measure the impact of an advertisement with regard to its production in the impact of an advertisement with regard to its production in the magazine “Business India”, December 1997 issue. The selected sample of the subscribers of the magazine is asked whether they have read an ad on product (x) in the magazine (December 1997 issue). Those who have read and not read are asked questions on some attributes (e.g., quality and price) of the product. The difference in the rating of the two groups is noted. This determines the effectiveness of the advertisement. This design has the merit over the “after’ only’ design because it avoids the influence of advance setting the experimental group (variable) in the otherwise natural setting. In this design. The experimental group is set to receive the treatment rather than exposing it to the treatment by its choice.

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