Assignment Details:

Question 1 (25 marks)
a) Apply the necessary transformation in PSPP/SPSS using the relevant variables from the data file to create the following new variables:
i) BMI
ii) BMI Risk Categories (Low vs Moderate vs High Risk)
iii) Blood Pressure Status (Normal vs Abnormal)
iv) A Composite Perceived Stress Score

Generate the frequency distribution tables for each of the new variables and cut and paste your PSPP/SPSS output into your answer.

Note:
For information on BMI and BMI Risk Categories, please refer to
https://www.healthhub.sg/live-healthy/410/Healthy%20Weight.

Abnormal Blood Pressure Status refers to systolic and diastolic blood pressure above 140mmHg and 90mmHg, respectively. For information on Blood Pressure Status, please refer to https://www.healthhub.sg/a-z/diseases-and-conditions/53/highbloodpressure.

For information on Perceived Stress Scale-4, please refer to http://www.psy.cmu.edu/~scohen/ under Scales > PSS 4-Item and PSS Scoring.
(20 marks)

b) Transforming BMI to BMI Risk Categories is an example of transforming a variable from a ratio scale to an ordinal scale of measurement. Examine the scales of measurement and analyse if it is appropriate to transform a variable on an ordinal scale to a variable on an interval scale and vice versa.
(5 marks)

Question 2 (45 marks)
a) Examine the following variables from the data file and identify the appropriate scale of measurement for each:
i) Physical Activity Level
ii) Age in Years
iii) BMI
iv) Blood Pressure Status
v) Perceived Stress Score
(5 marks)

b) Using PSPP/SPSS, apply the appropriate formula to calculate the descriptive statistics for the variables i) Age in Years, ii) BMI, iii) High Blood Pressure Status, and iv) Perceived Stress Score separately for participants with different Physical Activity Level. Present the results in one table and 4 separate graphs following the APA format.
Note: Please cut and paste your PSPP/SPSS output into your answer to demonstrate that you have used PSPP/SPSS.
(20 marks)

c) Examine the descriptive statistics for Age and identify one issue based on your understanding of what the researcher is interested to find out. Recommend what can be done to deal with the issue.
(5 marks)

d) Apply PSPP/SPSS on the composite PSS total scores to calculate the z-scores of each participant based on sample mean and standard deviation as well as the z-scores of each participant based on the population mean and standard deviation of 9.13 and 4.2, respectively. Interpret and report the proportion of z-scores that are at 70th percentile and above.
Note: Please cut and paste your PSPP/SPSS output of the frequency distribution table of zscores calculated based on sample mean and standard deviation and z-scores calculated based on population mean and standard deviation into your answer to demonstrate that you have used PSPP/SPSS.
(15 marks)

Question 3 (20 marks)
a) If the population mean and standard deviation of PSS for the null hypothesis is 9.13 and 4.20 respectively and the researcher hypothesized that the population mean and SD for PSS for the alternative hypothesis is 10.29 and 4.2 respectively, apply the necessary formulas to determine the statistical power of the test if the sample size is 50 and the alpha is set at .05 (two-tailed).

Note: Please show the necessary calculations in your answers. You may want to use the concepts of standard error, z-test, critical value and proportions in body and tail of distribution to help you answer this question. Round off your final answer to the nearest whole number.
(10 marks)

b) Using the same information for the null and alternative hypotheses from part a, calculate the statistical power if the alpha is reduced to .01 (two-tailed)
Note: Please show the necessary calculations in your answers. You may want to use the concepts of standard error, z-test, critical value and proportions in body and tail of distribution to help you answer this question. Round off your final answer to the nearest whole number.
(10 marks)