why is weighted versus stratified why is machine learning not used why machine learning is not being used in a nationally representative research study why is it a problem with weighted data what is the purpose of weighted weighted analysis what is the purpose of the weighted stratified analysis is weighted stratified what is the goal of a weighted stratified analysis why does machine learning ignore weight why is it difficult to do nationally representative data analysis? why is weighting a problem in machine learning why not using nationally representative data why are weighted and stratified data used when making data analysis why can't we use a weighted stratified analysis why is it difficult to use a standard weighted stratified analysis which is the goal of the weighted analysis in a machine learning study? why should i use weighted and stratified data sources why did machine learning not take into account weight and stratification variables in the nationally representative data source why is a weighted stratified analysis used in machine learning why is it not important to use weighted or stratified data in a research study?