how to construct an index that includes indicators like GDP and index e.g. HDI? to be more precise I want to construct an index to gauge current condition of the economy, so for that I am constructing an index that includes many variables. some of the variables are: GDP, HDI and consumer price index. there are two questions: one is how to include GDP of a country in the index? second one is that "can index like CPI or HDI can be part of the new index?"