Declining participation rates and data quality are serious problems in survey research. This is particularly true with reference to Internet surveys, where the absence of interviewers may pose an additional threat to interviewees’ propensity to respond and to complete questionnaire. In this paper we focus on the impact of: 1) e-mails and SMS reminders on survey participation; 2) data linkage on completeness of questionnaire. Our web survey aims at students registered during the AY 2015/16 in degree courses at the University of Milan Bicocca (young and educated per-sons, who are comfortable with internet use). With reference to the first issue, in web surveys e-mails and SMS can be used as remindersto improve participation rates. Relative to the second issue, the evaluation of data completeness implies to analyse several indicators, such as the percentage of missing values and response set, the lack of personal data, etc.
Our study assesses the impact of different types of reminders on survey participation through an experimental design of research and it represents an interesting example of data linkage between university administrative data and survey data. In particular, this data linkage exemplifies an opportunity to improve the completeness of the questionnaire compilation (reducing the number of items), and to reduce the percentage of inconsistent data (i.e. the percentage of data that are different for the same subject in administrative database and in the responses to the question-naire). As a matter of fact, the procedure of data linkage has the advantage of making more sustaina-ble the compilation for an interviewee. The researcher releases the respondent from providing the information that are already available through administrative sources.
To check our hypothesis, we consider eight experimental groups:
-T1.1-SMS, that will receive SMS only as a reminder and a questionnaire with additional questions about administrative information;
-T1.2-SMS, that will receive SMS only as a reminder and a questionnaire without additional questions about administrative information (through the use of the data linkage only)
-T2.1-E-mail, that will receive an e-mail only as a reminder and a questionnaire with
additional questions about administrative information;
-T2.2-E-mail, that will receive an e-mail only as a reminder and a questionnaire without
additional questions about administrative information (through the use of the data linkage
only);
-T3.1-E-mails and SMS, that will receive both SMS and an e-mail as a reminder and a
questionnaire with additional questions about administrative information;
-T3.2-E-mail and SMS, that will receive both SMS and an e-mail as a reminder and a
questionnaire without additional questions about administrative information (through the
use of the data linkage only);
-C.1-no reminders, that is the control group and it will not receive any reminders, but a
questionnaire with additional questions about administrative information;
-C.2-no reminders, that is the control group and it will not receive any reminders, but a
questionnaire without additional questions about administrative information (through the
use of the data linkage only).

Keywords: experimental design; reminder impact; response rate