In this model I would be trying to predict HDI of a country.
Model looks something like this: HDI(t) ~ Life Expectancy(t) + GNI (t)
However life expectancy and gni themselves are time variant independent variables. Is there anyway to account for this in linear regression such that i can predict
HDI(2018) using data from years before 2017? Is there anyway for linear regression to capture this?
Would be creating dummy variables like country be of any help?
As you mentioned HDI(t) is depending on Life Expectancy and GNI at the same time t so if you don't have their values in t it would be a guess.
By the way what are you looking for something like a and b in HDI = a * Life Expectancy + b * GNI?
You can assume a and b are time invariant and solve the problem for 2017 (or for several years and calculate mean) then you'll have them :)