Wilkinson Microwave Anisotropy Probe One-year data release Best-fit cosmological parameters from WMAP one-year results

| Parameter_ | Symbol | Best_fit_WMAP_only | Best_fit_WMAP_extra_parameter | Best_fit_all_data |
|---|---|---|---|---|
| Age of the universe ( Ga ) | t_0 | .4 ± .3 | – | .7 ± .2 |
| Hubble`s constant ( km⁄ Mpc ·s ) | H_0 | ± | ± | + − |
| ic Baryon content | Omega_b h^2 | .024 ± .001 | .023 ± .002 | .0224 ± .0009 |
| Matter content | Omega_m h^2 | .14 ± .02 | .14 ± .02 | .135 +.008 −.009 |
| Optical depth to reionization | tau | .166 +.076 −.071 | .20 ± .07 | .17 ± .06 |
| Amplitude | A | .9 ± .1 | .92 ± .12 | .83 +.09 −.08 |
| Scalar spectral index | n_s | .99 ± .04 | .93 +.07 −.07 | .93 ± .03 |