[Solved]a) Examine and comment on the normality of the following distribution of cholesterol values (mmol/L) using graphical and

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[Solved]a) Examine and comment on the normality of the following distribution of cholesterol values (mmol/L) using graphical and quantitative measures:

ASSIGNMENT FOR RESEARCH METHODS

AND DATA ANALYSIS

Complete all of the data analysis exercises that follow.  Check your data entry carefully and write/present your answers in a clear and precise manner.  It is expected that you justify the chosen statistics in each exercise.

Exercise 1

a)  Examine and comment on the normality of the following distribution of cholesterol values (mmol/L) using graphical and quantitative measures:

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5.3       6.2       3.4       5.8       7.5       7.2       7.9       6.2       8.1       7.4       7.3

7.5       6.5       5.2       8.5       5.5       5.6       7.9       4.3       3.8       5.6       8.5

3.5       4.8       5.1       5.5       6.8       5.5       4.3       5.7       7.3       8.4       6.9

7.8       4.2       7.6       3.9       5.5       3.1       3.0       4.5       5.4       6.9       6.8

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b)  Generate descriptive statistics for these data and comment on which measures of central tendency and dispersion should be used to summarise this sample. Also present and comment on the 95% confidence intervals.

Exercise 2.

a)  Analyse the two data sets below to test the hypothesis that there are no significant differences between the two groups of participants in the following variables: aerobic capacity (AC), systolic blood pressure (SBP) and body fat (BF).

Group 1 – Healthy weight

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AC¹     40.2    53.2    55.5    40.2    41.3    32.3    58.3    50.9    48.9    56.0    47.2    39.9    38.6

SBP²   121     125     120     122     128     118     122     125     122     123     121     118     131

BF³       24.0    19.0    22.5    18.0    32.0    28.5    15.0    15.5    17.5    18.5    26.5    22.5    20.0

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Group 2 - Overweight

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AC¹     27.5    42.2    21.3    32.3    32.3    30.9    30.2    35.2    36.2    44.3    40.0    30.2    44.2

SBP²   135     142     130     135     130     142     135     132     144     129     135     139     147

BF³       27.0    34.0    32.0    28.5    31.0    29.5    28.0    35.0    37.0    30.0    34.0    32.0    39.5

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¹ml^.kg^.min^{-1,  2} mm/Hg,³ %.

N.B.  Your analysis should consider appropriate diagnostic tests and the risk of committing a type I error.

b)  Participants in group 2 (overweight) had their aerobic capacityre-measured following six weeks of aerobic exercise training (see re-test data below).  Assess the hypothesis that there is no significant difference between the repeated measurements.

Group 2 (re-test)

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AC        29.5    42.8    31.3    34.3    31.3    35.9    31.2    36.2    36.4    45.3    40.7    35.2    43.2

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Exercise 3

Open the data file “Exercise_3.sav” into SPSS.  The file contains three ratio level variables, systolic blood pressure, diastolic blood pressure and age.

a)     Investigate the bi-variate relationships between the three variables.

Bear in mind the relevant diagnostic tests and the likely consequence of conducting multiple statistical tests on data from the same sample.

b)     Report your findings and comment on the key relationships observed.

Exercise 4

a)      Using the “Exercise_4.sav” data file, select the appropriate variables and statistical technique to test the hypothesis that there is no difference in the preference of a particular diet.  Each participant has tried all three different diets (Low Calorie, Atkins and 5:2 diet).  The ‘satisfaction’ score is given by the participant and is out of 100 (a rating of 100 = most satisfaction).  If necessary, consider the use of post hoc tests to provide additional information.

The type of data (level of measurement) is initially important when considering your choice of statistical test.

b)      Report and interpret your findings.

Exercise 5

a)      Using the “Exercise_5.sav” data file, select the appropriate statistical technique to test the hypothesis that there is no difference in systolic blood pressure due to an intervention of diet and aerobic exercise training lasting 6, 12 and 24 weeks.  Group 1 performs the intervention for 6 weeks, group 2 for 12 weeks and group 3 for 24 weeks.  Report and interpret your findings and consider the use of post hoc tests to provide additional information.

Exercise 6

a)      Open the data file “Exercise_6.sav” and identify the eight separate heart rate (HR) variables recorded during incremental treadmill running (four exercise levels x two trials).  Also identify the between-subjects variable within this data set and incorporate these three factors into your analysis of variance procedure.

b)      Report and interpret your findings.