Rubax, a U.S. manufacturer of athletic shoes, estimates the following linear trend model for shoe sales.

• Is there sufficient statistical evidence of an upward trend in shoe sales?
• Do these data indicate a statistically significant seasonal pattern of sales for Rubax shoes? If so, what is the seasonal pattern exhibited by the data?
• Using the estimated forecast equation, forecast sales of Rubax shoes for 2014(III) and 2015(II)
• How might you improve this forecast equation?