This is personal study note Copyright and original reference: https://www.youtube.com/watch?v=XCETXuhErsY&list=PLsri7w6p16vu3mMWzijxOmhrlvN23W04_&index=2&t=0s ================================================================================ relationship_between_independent_variables=association_analysis(data,scale_of_data) ================================================================================ Why associatio analysis is needed? Analyzing data is expensive If you can get more data from one analysis, it's efficient ================================================================================ Association analysis table scale analysis method which is used for asscociation analysis intervention by other variables correlation analysis interval scale, ratio scale partial correlation analysis yes Pearson correlation analysis no ordinal scale Spearman ordinal correlation analysis - cross analysis nominal scale Cross tabulation analysis -