A study says it used randomisation. That is a useful beginning, but the next question is what was randomised. Choosing which units enter a study and allocating the selected units to conditions are different operations with different purposes.
Draw the route into the study
Imagine a classroom exercise with 40 labelled seedlings. One decision is which seedlings to observe. A second decision is which observed seedlings receive each of two permitted growing conditions. Keep those decisions in separate boxes on a sketch.
The example is hypothetical and does not supply a horticultural protocol. Its purpose is to show that a careful allocation procedure cannot, by itself, tell us how the original set of seedlings was chosen.
Identify where the randomisation happens
The NIST discussion of completely randomised designs describes randomly assigning experimental units to factor levels. That is a design decision about allocation within the experiment. It is not automatically a statement that the units represent every plant someone might want to discuss.
In your reading notes, replace the single word “random” with a sentence: “the selected seedlings were assigned to the two conditions using the stated procedure.” If the report also explains selection, give that procedure its own sentence.
Match the conclusion to the route
Ask which population the authors want to describe and what evidence connects the observed units to it. Also ask what was controlled or recorded after allocation. No single design label answers every question about a study.
Our note on why a larger sample can still miss its intended population provides a complementary check. The useful habit is to follow the units from their source into the comparison, keeping selection, assignment and measurement visible as separate steps.