Which of the following studies would be considered longitudinal?
A study of soil erosion during the Asian monsoon season in 2015
A study of the effects of high sugar consumption on the health of children and adults
A study of the development of babies a month after birth and then again at age five
A study of post-recession unemployment rates
A longitudinal study involves repeated observations of the same variables over a period of time. Based on this definition, the study that would be considered longitudinal is:
A study of the development of babies a month after birth and then again at age five.
This study tracks the same subjects (the babies) over time, making it a longitudinal study. The other options do not involve repeated observations of the same subjects over time.