I have a dataset with socioeconomic information of the poorest households of a country. Each observation is associated with a vulnerability index (in a 0-100 scale) calculated using some of the variables of the dataset. This index is used to prioritize which households should have access to public programs. I want to replicate this index in other datasets that collected the same information (i.e that derive from questionnares that included the same questions). However, I don't know which variables were used to calculate it (some information was collected for a different purpose than construction of the index) nor the weight that was given to those that were actually used.
I was planning to predict the index using the variables of the dataset but I really don't know which method I should use. Any ideas?