Question 2: Calculate correlation coefficients between strength, height, and age. Report the correlation coefficients to two decimal places. What do these correlation coefficients tell us?
Click Analyze, Correlate, Bivariate. Select Quadriceps strength, Height, and Age into Variables. Make sure that Pearson is checked and so is Two-tailed. Click OK.
You should get the following output:
| Correlations | ||||
|---|---|---|---|---|
| Quadriceps strength (newtons) | Height (cm) | Age (years) | ||
| Quadriceps strength (newtons) | Pearson Correlation | 1 | .419** | -.417** |
| Sig. (2-tailed) | .006 | .007 | ||
| N | 41 | 41 | 41 | |
| Height (cm) | Pearson Correlation | .419** | 1 | -.338* |
| Sig. (2-tailed) | .006 | .030 | ||
| N | 41 | 41 | 41 | |
| Age (years) | Pearson Correlation | -.417** | -.338* | 1 |
| Sig. (2-tailed) | .007 | .030 | ||
| N | 41 | 41 | 41 | |
| ** Correlation is significant at the 0.01 level (2-tailed). | ||||
| * Correlation is significant at the 0.05 level (2-tailed). | ||||
Hence the correlation coefficients are:
quadriceps strength and height, r = 0.42, P = 0.006,
quadriceps strength and age, r = −0.42, P = 0.007,
age and height, r = −0.34, P = 0.03.
Strength is greater for taller men, smaller for older men, and older men are shorter. There is good evidence that the three relationships are present in the population from which these men come, strong evidence in the case of strength and height and strength and age.
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Last updated: 21 February, 2012.