What is the DV and how was the DV measured?

Lab 3 questions

Below are some basic answers to the questions discussed in the lab session – you may need to expand them with further details if you include them in your report. Remember that the highest marks are awarded for going above and beyond the information you have been given!

• For more detail on the study, look at the PowerPoint from Lab 3.
• For more detail on running the analysis, look at the Lab 3 worksheet (and the relevant PS1007 lecture and lab session).
• For more information on design elements (IVs, DVs, hypotheses, confounding variables etc.), look back over your PS1008 lecture slides from this year.
• For help with writing the report, look at the PS1008 resources on Moodle (e.g. guidelines for lab reports, lab report check list, information on APA formatting, and your lectures).
• Please also check the feedback you received from the first lab report to help you improve this time! If you have any questions about your feedback, get in touch with Dimitris or Kathryn and we can look at it with you.

Questions from Lab 3

1. What is the DV and how was the DV measured?

• The DV is the variable we measured – the participant responses to the lineup. We measured it by counting the frequency of response types that participants gave.
• Categorical
• Two: False Identification and Correct Rejection (see slide 40)
• The IV is the variable we manipulated – the instruction. It had two levels (the two conditions).
• The aim of the study was to see whether biased instructions (no warning of absent culprits) affected participants’ responses.
• The null hypothesis is that there will be no association between the IV and DV (i.e. they are independent of each other).
• The research hypothesis is that there will be an association between the IV and DV (i.e. they are not independent of each other).
• Independent measures/between subjects design
• Amount of exposure to the videos – particularly the culprit’s/lineup’s faces (Control: everyone watched the videos for the same length of time)
• Differences in instructions between groups (other than the intended one) (Control: everyone received identical instructions, other than the manipulated one)
• Individual differences between participants
• Second group may have overheard/seen through the door/been told more information than the first about the study
• Chi squared test of association/independence

2. What type of data is the DV (categorical or continuous)?

3. If the DV is categorical, how many levels does the DV have and what are the levels?

4. What is the IV, and how many levels does it have?

5. What was the aim of this study?

6. What is the null-hypothesis in this study?

7. What is the research hypothesis in this study?

8. What type of design is used in this experiment?

9. Name possible confounding variables in this experiment and explain how we have controlled for this.

10. Name other possible confounding variables that we have not controlled for.

11. What type of analysis do you think is appropriate for these data?