In: Statistics and Probability
The paper “Effect of Temperature on the pH of Skim Milk” (Journal of Dairy Research) reported on a study involving x = temperature (degrees oC) under specified experimental conditions and y = milk pH. The following data is a representative subset of the data used in the study.
X 14 18 23 24 26 38 38 40
Y 6.89 6.72 6.63 6.64 6.75 6.66 6.57 6.58
X 45 50 55 56 60 67 70 78
Y 6.59 6.48 6.42 6.41 6.38 6.34 6.32 6.34
a. Graph a scatter plot of X vs. Y. Does this data suggest a linear relationship between temperature and pH? Explain why or why not.
b. Show the estimated linear regression line on the scatter plot in (1.).
c. Calculate the sample correlation between x and y. Would you consider the correlation weak, moderate, or strong?
d. For a give temperature = 20 degrees oC, calculate the estimated value of Y using the regression line equation