If you’re going to use the terms criteria and phenomena in your writing, you should understand that they are plural, not singular. You can’t have one criteria or a single phenomena. What you can have is one criterion or a single phenomenon.
Conversely, you can’t have several criterion or multiple phenomenon. What you can have is several criteria or multiple phenomena.
I find it shocking that so many writers and speakers, even those for whom writing or speaking is central to their profession, misuse the plural form as a singular or the singular form as a plural. Here are just a few recent annoying examples:
From the Boston Globe: “While the magazine explains that criteria results are averaged, they do not say how much weight each criteria [read each criterion] is given in the final consideration.”
From the San Francisco Examiner: “The ideal conditions for long-term wine storage are consistent temperatures ranging between 54 and 58 degrees, ample humidity and darkness. If you have a corner in your basement that fits this criteria [read these criteria or perhaps this criterion], you’re my hero.”
From Forbes: “I only became aware of this phenomena [read this phenomenon] this summer.”
From Discover Magazine: “[M]any of these phenomenon [read these phenomena] are fuzzy on the margins.”
I could find many other illustrations, but you get the idea.