Hawaii tourism. Much of the public and private industry in Hawaii depends on tourism. The following time series plot shows the number of domestic visitors to Hawaii by air from the rest of the United States per month from January 2002 through December 2006 before the financial crisis of 2008.

Here is a regression model fit to these data with dummy variables for months and a Time variable that starts at 0 and counts months:
Response variable is: Domestic R squared = 95.5% R squared (adjusted) = 94.4%
s = 14336 with 60 - 13 = 47 degrees of freedom Variable Coefficient SE(Coeff) t-ratio P-value Intercept 312312 6925 45.1 60.0001 Time 2016.84 109.1 18.5 60.0001 Feb 8924.36 9068 0.984 0.3301 Mar 58693.7 9070 6.47 60.0001 Apr 20035.3 9073 2.21 0.0321 May 19501.0 9078 2.15 0.0369 Jun 90440.8 9084 9.96 60.0001 Jul 132893 9091 14.6 60.0001 Aug 96037.3 9099 10.6 60.0001 Sep -27919.7 9109 -3.07 0.0036 Oct 1244.42 9120 0.136 0.8921 Nov -12181.4 9133 -1.33 0.1887 Dec 39201.9 9146 4.29 60.0001

a) Interpret the P-value for the trend coefficient.

b) You are planning to visit Hawaii and hope to avoid the crowds. A friend says that September and November have the fewest average visitors. Why might that not be correct?

c) Do you find evidence of a seasonal effect? Explain.

d) How many tourists would you predict for Hawaii in April 2007 (month 63 of this series)?