Step $2$: Categorising Quantitative Research Designs according to their Timing

With regards to the timing categorisation of different quantitative research designs, answer the

following two questions:

$1.$ What is the difference between a cross$-$sectional research design and a longitudinal

research design? Use an example to illustrate the difference between the two.

$2.$ What is the difference between a retrospective research design and a prospective

research design? Use an example to illustrate the difference between the two.