This chapter sets out to explain the concepts behind the use of sampling in market research. It outlines some of the main options available to the survey designer and discusses the way sampling is carried out in practice. More complex topics are only introduced, with recommendations for more detailed reading.
Whenever sampling procedures for selecting the persons to be interviewed are used in empirical social research this is done in order to build models of the population by means of which the interesting phenomena can he studied. The size ratio between reality and the model will depend on how small the details of the basic population are which are to be found again and recognized with certainty.
Whenever sampling procedures for selecting the persons to be interviewed are used in empirical social research this is done in order to build models of the population by means of which the interesting phenomena can he studied. The size ratio between reality and the model will depend on how small the details of the basic population are which are to be found again and recognized with certainty.
These notes explain the method of sampling used for the Magazine Readership Survey carried out in Italy this year (ISPI, 1973 edition). The ISPI survey is a sample survey based on 21,000 interviews. It has been carried out each year since 1966 for the purpose of estimating the number of readers of the weeklies and monthlies of major interest from an advertising point of view. The 1973 survey is of particular interest because it provides concrete evidence of the advantages of using a stratified sample with non-proportional distribution between the various strata.
This paper examines some of the questioning procedures commonly used in leisure time activities. The likely pitfalls and biases are discussed and suggestions are made on how to avoid and minimize the possibility of their occurrence. Various sampling designs particularly useful in activity studies are examined from the point of view of obtaining maximum statistical efficiency, taking into account both administrative and response error considerations.
My task is to give an introduction into a discussion about a very important subject which we all know very well since a long time in every country - namely the sampling procedure. What may be the particular aspect of sampling problems on a European scale? Someone may have the opinion that a European sample is simply the addition of samples of the different countries. Up to a certain point this may be correct. Nevertheless, there will be a set of additional problems which we shall meet in practice - and therefore I want to pick up these extraordinary problems. I propose that we treat, at first, the sample of individuals and that we neglect - for the moment at least - those samples which are based on other units than individuals or households.
The British Market Research Bureau has conducted a number of surveys among farmers on topics ranging from mechanical equipment to fertilisers. This paper draws principally on the latest - and one of the largest - of these surveys, which was carried out in the second half of 1967 . The survey, producing over 700 interviews throughout Great Britain (i.e. England, Wales and Scotland, but excluding the Republic of Eire and Northern Ireland) was concerned with crop chemicals and livestock feedstuffs as well as providing information on company images and company representation, and was commissioned by a major manufacturer. The paper will be concerned not with the results of that survey, which remain confidential to our client, but with three main areas of techniques: 1. Sampling; 2. Questionnaire design; 3. Interview procedure.
The statistical sampling technique is nowadays generally used in surveys on the particular conditions and problems of the market for several products as well as in opinion surveys. The sampling technique is to supply the "most efficient" results by complying both with the necessity of exact information and of a minimised cost. The latter condition can be realised using the smallest sample size for the requirements of the research. For this purpose, the stratification appears to be a useful means by which the survey's field can be divided in sufficiently homogeneous segments, so as to obtain a smaller sample that the one obtainable with a simple random sample at the same level of statistical significance. More detailed aspects are to be taken into consideration, such as the necessity of attributing to the single strata a non-proportional weight; this situation can also exist after effecting the survey since more interviews can fail in some strata: A non-proportional, i.e. a biased sample, entails the problem of evaluating the reliability of the results obtained, for the purpose of assessing the correct estimate. This particular aspect will be dealt with in this note.
Selecting points of sales is a problem which many concerns, dealing with large consumption products, have to face frequently, either when they want their products to be sold in first class stores or when they want to start a promotional action with selected retailers or even when they want to launch a new product. Such selection is usually made in their commercial departments which dispose of a network of agents visiting regularly present and potential clients. But sometimes firms needing to make that kind of selection do not dispose of the proper equipment and they have to call in external sales forces or research companies. Sometimes ago, I had the opportunity to take part in an experience which I think would be interesting to be reported here. With some improvements and adjustments, it can be applied to other cases. At first I shall try to report the problem as it actually occurred and draw the main lines of the method and then I shall give the main results that were obtained.