Research Paper

Pages: 3 (709 words) Published: June 20, 2013
Statistical Analysis 2: Pearson Correlation
Research question type: Relationship between 2 variables What kind of variables? Continuous (scale/interval/ratio) Common Applications: Exploring the relationship (linear) between 2 variables; eg, as variable A increases, does variable B increase or decrease? The relationship is measured by a quantity called correlation

Example 1:
A dietetics student wanted to look at the relationship between calcium intake and knowledge about calcium in sports science students. Table 1 shows the data she collected. Table 1: Dietetics study data Respondent number 1 2 3 4 5 6 7 8 9 10 Knowledge score (Out of 50) 10 42 38 15 22 32 40 14 26 32 Calcium intake (mg/day) 450 1050 900 525 710 854 800 493 730 894 Respondent number 11 12 13 14 15 16 17 18 19 20 Knowledge score (Out of 50) 38 25 48 28 22 45 18 24 30 43 Calcium intake (mg/day) 940 733 985 763 583 850 798 754 805 1085

Research question: Is there a relationship between calcium intake and knowledge about calcium in sports science students? Hypotheses: The 'null hypothesis' might be: H0: There is no correlation between calcium intake and knowledge about calcium in sports science students (equivalent to saying r = 0) And an 'alternative hypothesis' might be: H1: There is a correlation between calcium intake and knowledge about calcium in sports science students (equivalent to saying r ≠ 0),

Data can be found in W:\EC\STUDENT\ MATHS SUPPORT CENTRE STATS WORKSHEETS\calcium.sav

Steps in SPSS (PASW): Step 1: Draw a scatter plot of the data to see any underlying trend in the relationship:

1

Loughborough University Mathematics Learning Support Centre Coventry University Mathematics Support Centre

A scatter plot can be drawn in MS Excel or in SPSS, as right, using the Graphs> Chart Builder options - choose Scatter/Dot - drag the Simple Scatter plot into the plotting region - drag the required variables into the two axes boxes - click OK [Note that the chart has been...