Gavin is testing the hypothesis that 'People are more likely to drop rubbish on the ground when there is already rubbish on the ground'. He is conducting a field experiment in a quiet street. His independent variable is whether the street already has rubbish on the ground or not. Gavin's dependent variable is whether people drop a leaflet given to them by a stooge onto the ground or not.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2018). The mark or mark type is shown in brackets.

1. [2] 1 mark for type of hypothesis.
2. 1 mark for the reason (even if name is incorrect). This may or may not be linked.
3. ∞ directional hypothesis / one-tailed hypothesis = 1 mark
4. ∞ because he is saying the way the IV will affect the DV (not just that there will be a difference) = 1 mark
5. ∞ as Gavin says rubbish will make people litter more, not just that it will have an effect on littering = 1 mark
6. [1] 1 mark for a way in which they are deceived.
7. ∞ They are given a leaflet as part of the experiment;
8. ∞ They do not know that they are being observed;
9. ∞ They do not know they are in an experiment / study / that they are participants;
10. [3] 1 mark for a reason (can be generic)
11. 1 further mark for detail (can be generic
12. 1 further mark for linking detail to Gavin's study.
13. ∞ (likely to be more) ecologically valid = 1 mark (generic)
14. ∞ as the participant is in the normal environment for the behaviour being studied = 2nd mark (generic)
15. ∞ and Gavin's participants are on the street, which is where people throw litter = 3rd mark (linked)
16. ∞ participants (likely to be) unaware that they are in a study = 1 mark (generic)
17. ∞ so fewer demand characteristics = 2nd mark (generic)
18. ∞ so Gavin's participants would not avoid littering because they knew they were being watched = 3rd mark (linked)
19. [2] 1 mark for a disadvantage (can be generic)
20. 2nd mark for disadvantage linked to Gavin's study.
21. ∞ (likely to be) few controls = 1 mark (generic)
22. ∞ so littering behaviour may vary because of other factors than the IV = 2nd mark (linked)
23. ∞ it might not work e.g. because of demand characteristics = 1 mark (generic)
24. ∞ because they might realise the litter-dropping stooge is not real = 2nd mark (linked)