Definitions:
Now by definitions,
1. All of the counselor's clients  → Population
2. The 55 randomly selected clients that were chosen for this study  →Sample
3. the proportion of all of the counselor's clients who stayed married  → parameter
4. The proportion of the 55 randomly selected clients who stayed married → Statistic
5. The answer "Yes" or "No" to the question on whether a client stayed married  : variable
6. The list of "Yes" or "No" answers to the question of whether the clients stayed married: data.