Which of these situations best describes a retrospective observational study? a.)
A student flipping a coin and analyzing its outcomes.

b.)
A doctor analyzing the medical history of a person.

c.)
A company using different promotions and analyzing its sales.

d.)
A clinical researcher giving a medicine to a person and analyzing its effects.

The correct answer is D. Elements are randomly selected from equal-sized blocks of the total population is NOT true regarding a randomized block design experiment

From the question we are told that one statement is NOT true regarding a randomized block design experiment.

Where

D) Elements are randomly selected from equal-sized blocks of the total population is Not True

In conclusion

The all other Options are true except option D which states that Elements are randomly selected from equal-sized blocks of the total population.

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