In: Statistics and Probability
You wish to be able to predict a swimmer’s 100 m freestyle time from her 50 m freestyle time. Here are the 50 m and 100 m free times for 20 competitive female swimmers.
50 m Free 100 m Free
24.89 50.35
26.04 52.17
25.18 50.87
25.24 50.23
25.68 51.66
25.02 49.85
26.03 52.15
25.96 51.30
25.23 49.88
25.10 50.00
25.60 50.46
25.35 51.09
24.70 49.26
25.49 51.11
25.95 51.56
25.61 51.86
25.64 51.24
26.04 51.73
25.01 50.03
24.92 49.46
The scatterplot using SPSS is:
The SPSS output is:
The hypothesis being tested is:
H0: β1 = 0
H1: β1 ≠ 0
The p-value is 0.000.
Since the p-value (0.000) is less than the significance level (0.05), we can reject the null hypothesis.
Therefore, we can conclude that the model is significant.
The regression equation is:
y = 2.910 + 1.883*x
Put x = 24.9, y = 2.910 + 1.883*24.9 = 49.8
Put x = 25.4, y = 2.910 + 1.883*25.4 = 50.7
Put x = 26.6, y = 2.910 + 1.883*26.6 = 53.0
Put x = 22.1, y = 2.910 + 1.883*22.1 = 44.5
80.7% of the variability in the model is explained, thus, this model can be used to make these predictions.