Final answer:
A cross-sectional study is an observational study that collects data from a sample of subjects at a certain point in time, without multiple time points. It is a relatively easy and cost-effective study design, but its results may be limited and weak. Researchers often use it to identify variables that may be linked, and then conduct further studies to explore these relationships.
Step-by-step explanation:
A cross-sectional study is a type of observational study that collects data from a sample of subjects just once at a certain point in time. It examines data at one point in time and does not involve collecting data from the same subjects at multiple time points. For example, a researcher might conduct a cross-sectional study to compare the dietary habits of different age groups at a specific moment in time. This type of study is relatively easy and cost-effective to conduct, but its results may be limited and weak, so researchers often use it as a starting point to explore further relationships between variables.