Q2) As cheese ages, various chemical processes take place that determine the taste of the final product. Assume that you have a dataset that contains concentrations of various chemicals in 30 types of mature cheddar cheese (n=30), and a subjective measure of taste for each type. You also have data on the concentration of acetic acid in the cheese (acetic), concentration of hydrogen sulfide (h2s), and concentration of lactic acid (lactic). All the data was collected a point in time.

You decide to regress the measure of taste on the concentration of acetic acid, hydrogen sulfide, and lactic acid, to see which ingredient has a significant impact on taste.

The variables in the regression are defined as follows:

1. taste: Subjective taste test score, obtained by combining the scores of several tasters (range: 0 to 60) (Units: Index points)
2. acetic: Natural log of concentration of acetic acid. The original units of the variable before log transformation were gm/cm³.
3. h2s: Natural log of concentration of hydrogen sulfide. Original units of the variable before log transformation were gm/cm³.
4. lactic: Concentration of lactic acid in gm/cm³

A scatter plot of the variables is shown below:

The results of the regression of taste on acetic, h2s, and lactic are as follows:

. reg taste acetic h2s lactic

Source |SSdfMSNumber of obs =30

-------------+------------------------------F(3,26) =16.47

Model |5020.6446831673.54823Prob > F=0.0000

Residual |2642.2423726101.624706R-squared=0.6552

-------------+------------------------------Adj R-squared =0.6154

Total |7662.8870529264.237485Root MSE=10.081

------------------------------------------------------------------------------

taste |Coef.Std. Err.tP>|t|[95% Conf. Interval]

-------------+----------------------------------------------------------------

acetic |1.5386453.0005010.510.612-4.6289747.706263

h2s |3.9152421.1531063.400.0021.5449986.285486

lactic |18.802358.3426142.250.0331.65385735.95084

_cons |-34.1349115.67628-2.180.039-66.35797-1.911851