Are any of these below examples of *longitudinal studies*? Either just one or both are correct..
a. Study done to consider occurrence/amount of the_ event_ of_ AIDS in_ patients_ infected_ with HIV disease
b. US census that takes place every 10yr (this is cross-sectional...but is it also longitudinal or no?)
Reference: longitudinal study is an observational research method in which data is gathered for the same subjects repeatedly over a period of time
Is it a or b? Thinking it could be a since b is cross-sectional for sure..but can it also be cross-sectional and longitudinal is the question...