Below are the results of two different linear regressions. The first only has an N of 10 while the second has an N of 43. The first has a very high association between the dependent variable and the independent variables overall (Adj R2 = 0.948, P = 0.003). The second one only has one variable in the model with a significant association with the dependent variable and a lower overall association (Adj R2 = 0.436, P < 0.001).
I am trying to understand some of the reasons for these two sets of results. The first seems spurious due to the small N. I am still having trouble understanding how the second could have an adjusted R2 as high as it does considering only one variable has a significant association with the dependent. What kinds of things might be going on here?