more than once. Moreover, there is no guarantee that each respondent is a member of the intended survey population. Finally, technical aspects, like pop‐up blockers, may prevent starting the survey questionnaire.
EXAMPLE 2.1 A web survey on technological communication and links between enterprises
The survey is carried out within the survey research activities now provided from the CASI (Center for Statistical Analyses and Surveys/Interviewing, Centro Analisi Statistiche e Indagini) seated at the ex‐Department of Mathematics, Statistics, and Informatics of the Faculty of Economics of the University of Bergamo. The survey topics were the use of e‐commerce, the collaboration with other enterprises and/or the belonging to groups, the markets, and the employment. The questionnaire was kept simple (6 pages of 40 substantial items, 1 welcome page, and 1 final page) and asked mainly for qualitative answers or for percentage data.
The survey addressed to about 2,000 firms of the provinces of Bergamo (used as pilot province), Brescia, Lecco, Varese, and Mantova (each province is in the Lombardy region in Italy) in the manufacturing and building sector. E‐mail addresses and stratification variables collection is from the administrative databases of the Chamber of Commerce for the Bergamo province and from a Unioncamere (Union of Chambers of Commerce) database for the other provinces.
The overall response rate was 21.9%, which is quite high considering that due to the quality of the list, 12% of the follow‐up contacts were explicitly wrong e‐mail addresses. Response rates by size of the firm, legal form, and economic activity did not differ very much. It is interesting to note that for small firms (less than 20 employees), the response rate was quite high compared with the other firm sizes.
Data collection took place, for the first wave, in spring 2000 and has been carried out according to the following steps:
Invitation to participate in the survey sent by e‐mail (survey presentation letter, a survey report as incentive, and other related advantages have been prospected).
A link of the individual firm address for completion of the questionnaire was included in the presentation letter. Therefore no identification code (id) and no password was required.
Three e‐mail reminders were sent (first reminder 14 days after the survey follow‐up and the two reminders with weekly periodicity). Mainly for research purposes a fourth e‐mail remainder was sent after the end of the survey period. As described in literature, the three reminders were effective in improving the response rate; the forth reminder did not have an effect.
A web survey questionnaire consists of one or more web pages. Respondents have to visit the website in order to answer the survey questions. Note that, at early times of web surveys, the Internet was only deployed as a medium to transport the empty questionnaire to the respondent and to transport the completed questionnaire back from the respondent to the survey agency. For example, a simple questionnaire form is implemented in an Excel spreadsheet. The respondents receive the spreadsheet as an attachment of an e‐mail. After they have downloaded this electronic form, they fill it in on their own computer. Completed questionnaire return is also by e‐mail. This type of survey is called an Internet survey, because it uses the Internet in a much broader sense, than just the HTML pages of the World Wide Web.
This chapter describes the various forms of online data collection, from simple e‐mail surveys to advanced web surveys. It shows how to use web surveys for different target populations, for cross‐sectional data collection, and for longitudinal data collection (panels). It discusses the main reasons for online data collection, the advantages and disadvantages, areas of application, and specific related problems.
2.2 Theory
Collecting data using a web survey has much in common with other modes of data collection. There are the usual steps, like survey design, fieldwork, data processing, analysis, and publication. At each step, however, consider the suitability of concepts and methods taken from traditional survey approaches (face‐to‐face, paper, telephone). Where necessary, implication for eventual questionnaire reception and completion on mobile devices needs to be borne in mind, and adequate adaptions need to be applied. This handbook examines the most important practical and methodological aspects of only web surveys and of mobile web surveys that need careful consideration. They relate on the following questions:
How to select the sample?
How to contact potential respondents?
How to construct a web questionnaire?
How mobile web surveys differ or are similar to web surveys?
How to make proper statistical inference based on a web survey data?
What is the impact of sampling and non‐sampling errors?
What are the problems and solutions for mixed‐mode surveys with web component?
How to handle web panels?
Detailed answers to these questions are in the other chapters of this handbook. The current chapter gives a general overview of different approaches of conducting web surveys. For each approach and each situation, different problems may occur, and therefore different methodological solutions are required.
2.2.1 TYPICAL SURVEY SITUATIONS
In this section, identification of typical situations, in which to conduct a web survey, is presented. A number of different key aspects lead to different survey situations:
Target population. There are general population surveys (among individuals or households), business surveys, specific population surveys (among specific populations like company employees, company customers, students at a university or school, or members of club), or open population surveys (among ill‐defined populations like consumers of a product or service).
Survey administrator. This can be a national statistical institute (NSI) or other official statistical government body, a commercial market research company, a university, or another research institute.
Cross‐sectional versus longitudinal data collection. A cross‐sectional web survey measures the status of a population at one specific point in time, based on a sample selected for that purpose. A longitudinal web survey (or web panel) is recruited; it is maintained to allow measuring change over time. Also, surveys on specific topics can be selected from the web panel.
Technical implementation. The questionnaire can be designed as a website on the World Wide Web. In this case, questionnaires are completed online. It is also possible to use the Internet as just a vehicle to transport a questionnaire form to the respondents. For example, a form in an Excel spreadsheet can be send as an attachment of an e‐mail. In this case, the questionnaire is completed offline. This approach was used at early stages of Internet diffusion. Now, the questionnaire is mostly, even not exclusively, completed online. The challenge is now the choice of the device used for reception and completion of the questionnaire and/or on the choice of the mode, if a mixed‐mode approach is adopted.
The choice of the target population for a web survey may have an impact on the magnitude of survey errors and particularly on non‐sampling errors. Such errors may partly be caused by selection problems (for example, under‐coverage) and
