Quiz: Stewart (2009)

The following quiz assesses students' ability to critically think about a piece of research.  The study looks at how anchors may affect people's payment of debt.

To assign this quiz to your students, please go to the student page for this quiz.

If you would like to give them a paper copy, please see the link below.

Student copy

The quiz

When customers use credit cards, they receive a monthly bill from the credit card company. In order to make sure that customers do not end up with a large amount of unpaid debt, there are laws requiring credit card companies to specify a minimum payment. According to Stewart (2009), this policy may do more harm than good.

Since minimum payments on credit-card statements are usually small amounts, Stewart wondered whether seeing an actual amount might make people pay less than they would otherwise have done.

The sample was made up of 413 participants that had been recruited via social media by a marketing research company.

Stewart gave the participants a mock credit-card bill of £435.76 (about $600). They were asked to imagine that the bill had arrived that morning and to consider how much they could afford to pay, and then to state how much they would pay. For half of the participants, the bill mentioned a minimum payment of £5.42.

Among those who wanted to pay the full amount, the presence of the minimum payment did not make any difference. However, those who were not able to pay the full amount offered to pay 43% less on average when presented with a minimum payment. When there was a minimal payment, the average amount offered was £99 and without the minimum payment, the average amount offered was £175.

In the real world, this would roughly double interest charges.

Questions

  1. Which design was used in this study? What was the independent and dependent variable?
  2. Comment on the internal validity of this study.
  3. Explain how one potential confounding variable may have affected the study.
  4. Explain one ethical consideration in this study.
  5. Comment on the ecological validity of this study.
  6. Comment on the population validity of this study.

Assessing responses

Each of the responses may earn up to a maximum of three marks, for a total of 18 marks.

1. Which design was used in this study? What was the independent and dependent variable?

Sample student response: The researchers used an independent samples design. The IV was the presence of a minimum payment that served as an anchor. The dependent variable was the amount of money that they were willing to pay.

Assessment: 1 mark for correctly identifying the design. 1 mark for identifying the IV.  1 mark for identifying the DV.

2. Comment on the internal validity of this study.

Sample student response: This experiment has relatively high internal validity. Although it is not stated, it appears that it was done under laboratory conditions.  This means that there was an attempt to control external variables. The IV was manipulated by the researcher - and each group only took part in one condition, so it is unlikely that they knew what the goal of the experiment was. The researcher also asked them how much they could afford to pay before asking them how much they would pay.  This was an important control because it controlled for the individual wealth of the individual participants.  Finally, the study had a control group that had no anchor that could serve as a baseline.

Assessment: 1 mark for a definition of internal validity. 2 marks for a clear justification of their position linked directly to the study.

Common errors: Students often say that it has high internal validity "because it was done in a laboratory."  This is actually not true.  A study may be done in a laboratory and have really low internal validity.  If this is the only answer, then a maximum of 1 mark is awarded.

3. Explain how one potential confounding variable may have affected the study.

Sample student response: One potential confounding variable is the education of the participants. Participants who have a good sense of finances or economics will perhaps be more able to guess what the goal of the experiment is and give the "appropriate answer." They may also be thinking about the amount of money that they will lose if they pay less this month, even if that is difficult for them to afford. This could also be linked to the age of the participants.  Younger participants may have less experience with credit card debt whereas older participants may be educated by personal experience where they paid only the minimum balance and ended up in serious debt.

Assessment: 1 mark for understanding the term "confounding variable." 1 mark for identifying an appropriate confounding variable. 1 mark for explaining how it may impact the study. Other appropriate variables include one's current financial situation, whether they have credit cards or not, cultural differences (e.g. long-term orientation), or their mood on the day of the experiment.

Common errors: Students often use "demand characteristics" as confounding variables. These are often less well supported because the link to the study is superficial - assuming that people will guess the experiment or that they will intentionally be dishonest or ruin the experiment.  Stronger responses tend to choose variables that are more directly related to the study. As you can above in the sample response, demand characteristics are addressed, but the reason why these are likely is clearly explained.

4. Explain one ethical consideration in this study.

Sample student response: One ethical consideration in this study is anonymity. Although the situation is artificial, the researcher asks the participants how much they could afford to pay. If anonymity is not guaranteed, the participants would not be willing to say that they could not afford to pay the full amount.  This would then influence the results of the study.  Since it is most likely that anonymity was guaranteed, the researchers found a clear difference between those that could afford the full amount and those that could not. 

Assessment: 1 mark for identifying and defining an ethical consideration. Up to 2 marks for linking the ethical consideration to the study.

Common errors: Students tend to gravitate to "undue stress or harm."  They write that the participants would be "humiliated" by having to admit that they could not afford to pay the bill. This is not really true. The participants have the right to withdraw from the experiment - and, in this case, they have clearly given consent to take part in the study.

5. Comment on the ecological validity of this study.

Sample student response: This study has relatively low ecological validity because at all times the participants know that they are taking part in a study. They are not spending their own money and this is more of a "thought experiment" so it may not reflect what would actually happen if they received the bill themselves.  The question about whether they could afford to pay it off may have actually led to people saying that they would then pay the full amount.  Maybe in a non-experimental situation, they would know that they could pay it off but still choose not to.

Assessment: 1 mark knowledge of the meaning of ecological validity. Up to 2 more marks for a clear link to the study.

Common errors: Students often write that the sample is representative or not - and that this affects the ecological validity.  This is incorrect.  This affects the external validity - which is based on both ecological and population validity.

6. Comment on the population validity of this study.

Sample student response: The sample was a self-selected sample that was gathered by social media.  This may mean that the age of the people in the study is limited and does not reflect the general population. We also have no idea about the diversity of the sample.  We know that cultural dimensions have an effect on how people make decisions.  If the sample is homogeneous, then this will limit the potential for generalizing the findings.

Assessment: 1 mark for a definition of population validity (or a clear indication of understanding). 2 marks for explaining how the sample may affect the ability to generalize the findings.

    Suggested markbands

    7: 16 - 18

    6: 14 - 15

    5: 11 - 13

    4: 9 - 10

    3: 7 - 8

    2: 5 - 6

    1: 0 - 4

    All materials on this website are for the exclusive use of teachers and students at subscribing schools for the period of their subscription. Any unauthorised copying or posting of materials on other websites is an infringement of our copyright and could result in your account being blocked and legal action being taken against you.