The dispersion and mean trends of r -process abundances in metal-poor stars are discussed based on a model of diverse supernova sources for the r -process .
This model is unique in that its key parameters are inferred from solar system data independent of stellar observations at low metallicities .
It is shown that this model provides a good explanation for the observed dispersion and mean trend of Eu abundances over -3 \lesssim { [ Fe / H ] } \lesssim - 1 .
It is also shown that this model provides a means to discuss r -abundances in general .
For example , the Ag abundance in any metal-poor star with observed Eu and Fe abundances can be calculated from the model .
This approach is demonstrated with success for two stars and can be further tested by future Ag data .
The dispersion and mean trend of Ag abundances in metal-poor stars are also calculated for comparison with future observations .