Longitudinal research gives us insight into the development of affairs. Sometimes the questionnaire is administered to the group be even intervals, and sometimes the questionnaire is administered to a new group of individuals.
The Social Science Research Institute (SSRI) has conducted numerous longitudinal research over the years. Spring 2020, the institution began a longitudinal survey on the attitude of Icelanders to various affairs related to the COVID-19 pandemic. A survey was sent every day to a new sample to follow the development of attitudes.
SSRI can manage all aspects of conducting a longitudinal survey; and handles drawing a sample when that applies, making a questionnaire, setting up the survey, collecting data and analyzing it.