A skeptic suggests that reduced sea ice isn’t due to global climate change at all. He offers the following model, including Year since 1979 as another predictor as an alternative to the model in Exercise 23: (Data in Sea ice):

a) The coefficient of Mean global temp now has a P-value of 0.6409. Interpret that value in the context of this model.
b) Would you conclude that global temperature is not, in fact, related to sea ice extent? Why or why not?
c) What do you think might be the reason that the coefficient and P-value for Mean global Temp are so different between this model and the one of Exercise 23?

Data From Exercise 23

Climate scientists have been observing the extent of sea ice in the northern Arctic using satellite observations. Many have expressed concern because in recent decades the extent of sea ice has declined precipitously—possibly due to global climate change. Here is an analysis relating the minimum (September) Extent of sea ice (km2) to the Mean Global Temperature (°C) for the years 1979–2015:

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Response variable is: Extent No Selector K squared = 14.3% s = 0.5/22 with 3/3 = 34 degrees of freedom Variable Intercept Mean Year since 1979 global Temp Coefficient SE(Coeff) t-ratio 15.6311 16.39 0.954 -0.515332 -0.078959 1.095 -0.471 0.0198 -3.98 P-value 0.3468 0.6409 0.0003