Stats Beginner

[Statsbeginner]

Hello everyone,

I am a psychology undergraduate who has been set a formative assignment (which means its not worth anything but still has to be done) using SPSS. I was wondering if anyone could help me answer these questions as I am struggling and My lecturer scares me and isn't very nice. I know it isn't worth anything but I want to understand the questions as I might come across similar questions later in the term. Any help given will be greatly appreciated:


QUESTIONS: 
1. Suppose that a group of researchers areinterested in the idea that high fertility can alter women’s mood, and thereby influencedepression. Because a woman’s menstrual cycle phase is linked to her fertility,they conduct an observational study to test whether women’s menstrual cyclephase predicts their feelings of depression. Participantsreported the day of their menstrual cycle and filled out a questionnaire aboutdepressive symptoms. Each woman participated only once. Women who were on days9-15 of their cycle were classified as being in a “high fertility” group, andthose on days 19-25 were classified as “low fertility”. High scores on thequestionnaire indicate that the participant feels more depressed. Scores forthe two groups are shown below. The two columns represent different setsof women. a. What is the null hypothesis in this experiment? (1)

b. The researchers’ hypothesis is that depression scores change according to the fertility phase of the menstrual cycle. What would be an appropriate statistical test for this hypothesis? (1)
c. Enter this data into SPSS, being careful to consider whether it is between-groups or within-group design. Perform the analysis you have described in part b. Present your results appropriately for inclusion in a results section of a scientific report. Report your p-value as a two-tailed test. All statistics should be reported to 2dp. (7) 

Suppose now that the researchers had chosen a different analysis, which included women who were menstruating or premenstrual. The researchers define this third group of women as anyone who is on days 26-28 or days 1-5 of their cycle. The data for this group is shown below. d. The researchers use ANOVA to analyse this data. They want to compare ratings during the high fertility phase with those during the low fertility phase, and then to compare the high fertility phase with the PMS/menstrual phase. They hypothesise that scores will differ between these groups, and do not make specific predictions about whether they will increase or decrease. What is the name for the planned contrasts they should choose inSPSS? (2)

e. Is there evidence of a significant overall effect of menstrual cycle phase on depression scores? Is there evidence of a significant difference between women in the high and low fertility phases? Is there evidence of a significant difference between women in the high fertility and the PMS/menstrual phase? State the appropriate statistics to justify your answer in each case. Report all statistics to 2dp. (8)

f. Is there evidence of a violation of the assumption of homogeneity of variance? State the appropriate statistics to justify your answer. Report statistics to 2dp.(4)

g. Create a bar graph to display this data, including all the required elements for publication in a scientific report. (7)30 Marks

2. Some researchers are interested in whether a person’s physical attractiveness is related to the salary that they receive in their job. To explore this, they collect photographs of 80 people, along with data about their annual salary and their age. The photographs are independently rated for attractiveness on a scale of 0 to 7. The researchers enter this data into an SPSS data file, with each row representing a person, and the columns representing their age, their average attractiveness rating, and their salary. (data available) 

a. Using this data, create a scatter graph of the relationship between physical attractiveness and salary, making sure to include all the elements appropriate to a scientific publication. (2) 

b. From looking at this graph, would you hypothesise that there is a significant relationship between physical attractiveness and salary? (1)

c. What is the statistical correlation between age and salary in this sample? Report your analysis in full, with statistics, in a way that is suitable for a scientific report.(7)

d. The researchers hypothesise that the effects of age on both attractiveness and salary might be “masking” the effects of attractiveness on salary. They hypothesise that 1) age will be negatively related to attractiveness, and hence that 2) after controlling for age, there will be a positive relationship between attractiveness and salary. To test their first hypothesis, they perform a linear regression, to explore the relationship between age and attractiveness. Perform a linear regressionyourself, and report the results in full. Include a sentence, in plain English,to describe the relationship between age and attractiveness. Report statisticsto 2dp. (10)

e. The people in the sample are all aged between 17 and 50. Perform a regression analysis of the relationship between age and salary,and use this to estimate what the salary would be for a 64 year old. Report al lyour statistics to the nearest whole number.(6)

f. Perform a hierarchical (two-step) linear regression to test whether attractiveness predicts salary after controlling forage. Is attractiveness a statistically significant predictor of salary when age is included in the model (Yes/No)? Report the relevant p-value to 3dp. Is attractiveness a positive or negative predictor, or neither? Which statistic did you look at to answer this question? How much variation in salary does attractiveness explain, aftercontrolling for age? Which statistic did you look at to answer this question? Is the researcher hypothesis from part d supported (Yes/No)? (14)40 Marks

3. Some researchers are interested in whether competitive behaviours operate to show off skills to potential romantic partners. They hypothesise that heterosexual men who are asked to engage in a competitive task will perform differently when being observed by female rather than male experimenters, and especially if the task relates to skill rather than simply hard work. To test this hypothesis they randomly allocate participants to a skill-based or an effort-based task, and to be observed by either a male or a female experimenter while they complete the task. The researchers enter this data into an SPSSdatafile, with each row representing a participant, and three columns representing whether they performed an effort or skill-based task, whether they were observed by a man or a woman, and their score on the task. (data Is available) 

a. Perform an analysis to test the researchers’hypotheses, including all the required follow up tests and descriptives that you believe are necessary. Write up this analysis in full, describing any statistical assumptions that you think are necessary, or explaining why youthink that such tests are not necessary. You should report effect sizes as wellas statistical significance. 
(14) 

b. Fill in the following table with the statisticsyou produced in your analysis. Pay attention to the number of decimal placesrequired.

Effect:

F-value (2 decimal places)

Partial eta squared (2 decimal places)

Gender

Task type

Gender*Task type

(9)c. Produce an appropriate graph to show yourfindings.(7)


Thank you all in advance,

Kind regards,

Katie

[fuzzylogician]

Hi there, this forum is for students applying to graduate school, it's not for help with homework. You should either talk to your lecturer, nice or not, or find another, more appropriate online community to help you. For what it's worth, I doubt anyone will solve all this for you. There are probably over a dozen questions here and you have not indicated that you have made any effort to solve this yourself. A better approach is to ask more specifically about the places where you are stuck, instead of posting the entire assignment as-is.