Figure 2: Mean and (cosmic) variance of the angular two-point correlation function as expected from cosmological inflation (arbitrary normalization). Only statistical isotropy, Gaussianity and scale invariance are assumed. Tensors, spectral tilt, reionization and the integrated Sachs-Wolfe effect are neglected for the purpose of this plot. Comparison to the prediction from the best-fit CDM model (Figure 5) reveals that these corrections are subdominant. Note that cosmic variance errors at different values of are very highly correlated.