Vital statistics include: MCQ with Answer and Explanation

Explanation:
Natural increase is driven purely by vital events (Births minus Deaths), ignoring migration.

Explanation:
An event with probability zero cannot occur under the given probability model, defining it as impossible (though in continuous distributions, point events have P=0 but are not impossible).

Explanation:
Mailed questionnaires often suffer from low return rates, and respondents who reply may differ systematically from non-respondents, introducing bias that is difficult to assess or correct.