The large-scale research project known as the Midlife in the United States (MIDUS) National Survey included questions pertaining to personal health that was sent out to 7000 participants between the ages of 25 and 74. This type of study in which data is gathered at one time from groups of participants who represent different age groups is an example of what general type of research design?

Cross sectional study.

Explanation: Research studies may be conducted from various purposes such as to establish causal relationship, give insight or extensive knowledge on certain subjects and others. However, Studies conducted to involve large number of participants from a population which isn't aimed at providing a definitive causal relationship between a particular variable of interest. Cross sectional studies are usually collected at a time and it involves subjects with various level of variability such as age, gender and so on. Cross sectional study are usually employed in giving a broad view or description of a particular topic.