Concern over the weather associated with ElNino has increased interest in the possibility that the climate on earth is getting warmer. The most common theory relates an increase in atmospheric levels of carbon dioxide (co2),a greenhouse gas, to increases in temperature. A regression analysis of the mean annyal co2 concentration in the atmosphere at the top of Mauna Loa in Hawaii (in parts per million) and the man annual air temperature over both land and sea across the globe (in degress C) for 44 years was performed. Assume all conditions are met for a simple linear regression inference.
| Variable |
coefficient |
SE (coef) |
| Constant |
15.54 |
0.26 |
| co2 |
0.003 |
0.0008 |
R-squared = 32.1%
s=0.075
a) Calculate the t-statistic for this problem.
b) How many degrees of freedom for the t-statistic problem have?