Thus by 1803 there were two known rare earth elements, yttrium and cerium, although it took another 30 years for researchers to determine that other elements were contained in the two ores ceria and yttria (the similarity of the rare earth metals' chemical properties made their separation difficult).
For instance, students who pursue a Ph.D. in psychology usually take from five to seven years depending upon required coursework as well as internship and supervised residency requirements.
Relevance. Rating Newest Oldest. Best Answer: It generally takes 2 years to complete a master's and after that I would say at least 3-4 to complete a Ph.D. although many doctorates take much longer than that: sometimes up to 6-8 years. wrote mine in two years, but I know people who took much longer. If you are doing clinical psychology, it could take longer, because you may need to do clinical training. Someone suggested getting a Master's first.