Poster abstract details

We have found a strong correlation between small filling factors and large $t^2$ values in planetary nebulae. We have also found that in general the filling factor for Type I PNe is smaller than for Type II PNe. These results imply that the abundance correction due to temperature inhomogeneities in general is larger for Type I PNe than for Type II PNe. This difference helps to reproduce the expected abundance difference between PNe of Type I and II predicted by Galactic chemical evolution models.