A factory operator hypothesizes that her unit output costs (v) depend on wage rate (x). other input costs (r), overhead costs (x), and advertising expenditures L.). A series of twenty-four monthly observations were obtained, and a least squares estimate of the model yielded the following results: y 75+24+.56x32x+23% (07) (12) (23) (.05) R-79 d = .85 The figures in parentheses below the estimated coefficients are their estimated standard errors. What can you conclude from these results?