In all colleges and universities, there will always be those bad professors, favorite ones, good teachers and bad teachers. But a research suggests that having a good teacher can have a lasting positive effect on the students' lives after graduation.

According to Education World, an Ivy League study suggests that good teachers can impact on the future earnings of their students. This research conducted by economists from Harvard and Columbia which involved 2.5 million people for over 20 years found that those who we taught by good teachers during their elementary and middle school earned higher income as adults compared to their peers who did not.

The study which these economic professors have presented to a dozen of their colleagues in several seminars is said to be the largest look yet at the controversial "value added ratings" which measures the impact of individual teachers to the students' test scores, the New York Times reported. This highlights the importance of hiring quality teachers and the method to measure the quality.

The study's findings is more focused on shedding a new light on differentiating bad from an average teachers. In fact, there are already a number of school districts in Washington and Houston that have begun using value-added metrics to help in decision-making on the teachers to be hired, paid and even those that need to be fired.

Many supporters agree that this is a good way to make sure that educators are held accountable for the quality of their jobs and that it is also helpful when it comes to improving the educational outcomes of millions of students. On the other hand, there are also some detractors who disagree because they say that isolating the effect of a single teacher might be more difficult than it seems and that it might be unfair.