An intervening variable facilitates a better understanding of the relationship between the independent and dependent variables when the variables appear to not have a definite connection. They are studied by means of operational definitions and have no existence apart.
Macroevolution is the process that takes place over several thousands of years and describes how humans have evolved from primates and how reptiles turned into birds. Microevolution leads to small changes in the same species whereas macroevolution leads to the creation of a new species from parent species.
The major conceptual difference between US GAAP and IFRS; is that US GAAP is rules based and IFRS is principles based. This means that IFRS will not include the detail that the United States is used to in providing guidelines.