The conversion of RLH to LL is not clear to me. Especially the step B. How do we get the total LL across respondents from the individual LL? Could you explain that with a formula?

Based on the total LL, I can then apply the following formula to get the total Pct certainty of my model? Pct Certainty=(LL final model- LL Chance model)/(-LL of the Chance model). So if I get a total LL of 0.69, I will have a Pct Certainty of (0.69-(-10))/(-10)=0.66.

Thank you