auto_stage0 - elimination of non significative variables
auto_stage1 - search of a statistically admissible regression
auto_test - build specification tests function and vector of names
automatic - automatic general to specific regression
def_results - creation of two tlists for subsequent regressions
ols1a - ordinary least squares
ols2a - ordinary least squares
ols3a - ordinary least squares
test_spec0 - five default specification tests