The two studies serve different purposes but must share one measurement logic. Here is how they relate.
Baseline: establishing the starting position
A baseline measures indicator values before, or at the very start of, program implementation. It sets reference values against which change will later be assessed, and often refines targets that were set on assumption during proposal development.
Endline: assessing change and performance
An endline measures the same indicators at, or near, program completion. It assesses the extent of change, performance against targets, and, depending on design, the plausibility that the program contributed to observed change.
What must stay constant between them
Comparability is the whole point. Indicator definitions, recall periods, question wording, sampling approach and unit of analysis should remain consistent unless there is a documented reason to change and a plan to handle the break in series.
- Same indicator definitions and calculation formulas
- Same target population and sampling logic
- Same key question wording and response options
- Documented deviations, with their implications stated
Change is not the same as impact
A baseline-endline comparison shows change over time. Attributing that change to the program requires a counterfactual, a comparison group, or a design that credibly accounts for what would have happened anyway. Reports should be precise about which claim the evidence supports.