A research design in which the same individuals or events are studied over several points in time This design allows researchers to observe changes over time
relaxation time (T1): the time it takes after a pulse in NMR for the nuclei to get the same spin up/spin down ratio they had before the pulse Also called spin-lattice relaxation
over an extended time; "a longitudinal study of twins" running lengthwise; "a thin longitudinal strip"; "longitudinal measurements of the hull" of or relating to lines of longitude; "longitudinal reckoning by the navigator