Select all statements that are correct.
1. By including both landline telephone and cellphone households, the survey more accurately represents the target population of American adults.
2. The person who answers the phone might be biased toward a certain gender or age. Including both landline telephones and cellphones in the survey is not necessary.
3. Women are more likely to agree to participate in the study.
4. Cellphone‑only households may differ from landline households in a number of ways including socioeconomic factors, ethnicity, age, etc.
5. Gallup selects the adult with the most recent birthday in a household to select for the oldest member of the household.
6. Gallup selects the adult with the most recent birthday in a household to randomize the participant selected from the household. 7. Gallup selects the adult with the most recent birthday in a household to select for the youngest member of the household.
8. Women are more likely to answer the phone.

1 When the target group is American adults, who very often have landline telephones and cellphones, it can be argued that including them will be more accurate.

4 This may be true; I can imagine that there are people, socioeconomically different, who don´t have (access to) landline phones.

6. Birthday doesn´t have anything to do with age, as suggested in nr. 5 and nr. 7. Birthyear does. The selection of most recent birthday in a household is a good way of selecting at random.

2, 3 and 8 are statements that don´t have any scientifical reasoning.