Carrie is studying when people decide to eat meals and the quality of their sleep. She is worried about variables that could affect when people decide to eat meals, and the effect these could have on validity.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.

1. 1 mark for variable
2. When someone normally eats = 1
3. Culture/ethnicity/lifestyle = 1
4. How busy they are = 1
5. How much someone normally eats at meals = 1
6. Their age / young/old eat earlier = 1
7. If they are dieting / have special dietary needs = 1
8. Drugs affect hunger: tea/coffee/alcohol = 1
9. Hunger/thirst = 1
10. 1 mark for explanation of effect on validity: must link effect of variable (e.g. food/hunger/thirst) and sleep
11. If demand characteristics change meal times, they may be hungry when they sleep = 1
12. If they eat a lot / often / don't get hungry when they eat may not affect their sleep = 1
13. 1 mark for variable
14. Whether there are nice food smells when they are eating = 1 variable
15. If they have a job that stops them eating at normal meal times = 1 variable
16. 1 mark for explanation of effect on validity
17. Whether there are nice food smells: this might make them eat earlier/more which could affect their sleep = 1
18. If they have a job that stops them eating at normal meal times: would make them eat less regularly affecting their sleep = 1