Road construction contracts in the state of Florida are awarded on the basis of com~etitive, sealed bids; the contractor who submits the lowest bid price wins the contract. During the 1980s, the Office of the Florida FLAG wants to model the price (y) of the contract bid by lowest bidder in hopes of preventing price-fixing in the future.

a. Do you detect any multicollinearity in these variables? If so, do you recommend that all of these variables be used to predict low bid pricey? If not.
which variables do you recommend?

b. Using the variables selected in part

a, fit a firstorder model for E(y) to the data stored in the file.

c. Conduct a complete residual analysis on the model fit in part

b. Do you detect any outliers? Are the standard regression assumptions reasonably satisfied?

1042 Teaching Sociology (July 1995) developed a model for i the professional socialization of graduate students worki I ing toward their doctorate. One of the dependent variables modeled was professional confidence. y, measured on a 5-point scale. The model included over 20 independent variables and was fitted to data collected for a 1 sample of 309 graduate students. One concern is whet he^
multicollinearity exists in the data. A matrix of Pearson product moment correlations for ten of the independent variables is shown on page 622. [Note: Each entry in the table is the correlation coefficient r between the variable in the corresponding row and corresponding column.]

a. Examine the correlation matrix and find the independent variables that are moderately or highly correlated.

b. What modeling problems may occur if the variables, part

a, are left in the model? Explain.