Name the study in which the observation or data are referred to for more than one point of time?

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E6 NursingResearch Polit 11e Part 1 p. 177-179
E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 62-64
E6 NursingResearch Suresh Sharma 5e Part 1 p. 191-193
Practise the full DSSSB - 29 August 2019 (Shift-1)
Attempt every question from this paper in a timed mock, then review the full solution for each one.