Statistics
The researchers recruited 120 adults and recorded their sex (V1: 1 = female; 2 = male) and BMI (V2: 1 = underweight; 2 = normal; 3 = overweight). Participants reported their level of hunger (V3) – at the start of the study – on a Likert scale ranging from 1 = “not hungry at all” to 9 = “extremely hungry”.
Participants then completed a range of self-report measures:
Kirby Monetary Choice Questionnaire: 27 items, each presenting two choices: either an immediate reward (e.g., “$55 today”) or a larger delayed reward (e.g., “$75 in 61 days”). The higher the overall score (V4), the more likely is the person to choose the smaller, immediate rewards.
Brief Sensation Seeking Scale: 8 items, scored on a Likert scale from 1 = “strongly disagree” to 5 = “strongly agree”. Example item: “I like wild parties”. The higher the overall score (V5), the more likely is the person to seek novel and stimulating experiences.
The Tightwad-Spendthrift Scale: 4 items, scored using either a 1-11 (item no.1) or 1-5 (items 2-4) ratings. The higher the score (V8), the more difficultly people have in controlling their spending. Tightwads (i.e., those with low scores), on the other hand, tend to become anxious and experience pain when they have to spend money.
The Positive and Negative Affect Schedule – Expanded form (PANAS-X): Participants are presented with a list of 60 adjectives (e.g., confident, joyful, upset, angry), and are asked to indicate the degree to which they feel each of these positive and negative emotional states in general. Items are scored on a Likert scale ranging from 1 = “very slightly or not at all” to 5 = “extremely”. V9 indicates positive and V10 negative affect scores. High scores on V9 and V10 represent high levels of positive and negative affect, respectively.
Please note that you are required to answer ALL SIX questions:
1. For the overall sample (i.e., not separate groups), examine all the variables from V3 to V10 for any violations of the normality assumption. Pick a variable that you feel violates the assumption. Run at least three transformations on that variable, and then make a decision as to which transformed version leads to the best improvement. If none of the transformed versions leads to any improvement (i.e., meet the assumption of normality), then continue to use the original variable. Write up the procedure you followed for that one variable (ignore the others that you tested) in the form that you would write it up were it part of a research report. For all of the remaining questions, use the transformed variable (assuming that you decide that the transformed variable is an improvement on the original; otherwise, stick with the original). [10 marks]
2. Test the homogeneity of variance assumption on variables V3 to V10, with variable V2 as the grouping variable/factor. Pick one variable that you feel violates the assumption and run the appropriate power transformation on that variable. Write up the procedure you followed for that one variable (ignore the others that you tested) in the form that you would write it up were it part of a research report. For all of the remaining questions, use the transformed variable (assuming that you decide that the transformed variable is an improvement on the original (i.e., using the transformed variable, the assumption is met); otherwise, stick with the original). [5 marks]
3. Carry out a contingency table analysis using c2 to answer the question of whether there is a significant relationship between sex and BMI. In other words, are males and females equally represented across the three BMI groups? Show a bar chart of this relationship and present the descriptive statistics in a properly formatted APA table. Make sure that after running the c2 analysis you use the standardised residuals to help interpret the result. [5 marks]
4. Is there a sex difference for the scores on the Kirby Monetary Choice Questionnaire (V4)? Is there a sex difference on Brief Sensation Seeking Scale (V5)? Write up the results in APA style, including properly formatted APA-style graphs of the means and an APA style table of the descriptive results (you can provide the results for both variables in the one table or in separate tables). Two separate analyses and two graphs are required for this question, and at least one table. [5 marks]
5. Show a correlation matrix of the eight continuous variables, with significance levels. Present the matrix as a properly formatted APA-style table, then pick two significant correlations from the matrix and write up these results in APA style. [5 marks]
6. Is there a significant difference between commission errors to happy (V6) and sad faces (V7)? Pick an appropriate significance test to answer this question, and present the results in APA style, along with a properly formatted APA bar chart and a table of the descriptive results. [5 marks]